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Between The Lines – 1997

This document is the continuation of Between the Lines 1996. Our “Between the Lines: Preface” document contains important introduction information that will help you to understand this context and it’s objectives. If you have not already read that preface, we recommend you do so.


Page 44 – Westcoast GSXR – This article is exceptionally prominent for several reasons that go beyond the face value of these pages. Westcoast Performance Products and it’s owners (Bob and Anita Zantos) have received more industry awards than anyone else in the aftermarket business. Add to this that WPP has been chosen by Bombardier to field their premier IJSBA tour effort for the last two years. Within the last year, WPP has amassed the largest group of top talent ever assembled for one pwc pro team. During these two years of racing development, there has been a virtual “cone of silence” surrounding the equipment created by the WPP team technicians. The expectations of this machine (like the price tag) are understandably very high. This article is the first editorial piece, of any depth, to be printed about the much photographed and anticipated WPP machines. This certainly rates as a “scoop” for the Splash editors.

It is impossible to know the actual circumstances of a boat test like this. However the boat makers usually intend to offer enough information to showcase their manufacturing abilities, as well as spark interest in potential customers. The editor, on the other hand, wants to fill the needs of the readers by providing the maximum amount of performance and price information. We believe that this article falls far short of providing the full measure of that information. Either not enough questions were asked, or not enough information was offered. Foremost in the information vacuum is the price, (or any prices for that matter). WPP has elsewhere indicated that the price will be about $15,000. While this seems like a great deal of money, the builders of other composite racing pwc’s consider it to be surprisingly inexpensive. While machines like this have a way of getting much more expensive at delivery, we will take WPP at their word for the $15k.

By far the most impressive thing about this boat is the weight reduction offered by the composite hull. This machine is 125 pounds lighter than a standard GSX and 43 pounds lighter than the (already very light) XP. All the visible components of this machine appear to be nicely crafted (as they well should be). There seems to be nothing second class about the manufacturing or fabrication of a single piece.

While Tom Kerker did his best to describe the handling abilities, both he and the WPP technicians should have made some effort to offer that message to the readers in a more definitive way. The only way we can think of, would have been to have a stock GSX hull with the identical driveline installed. Not many shops would want to go to this great trouble for a magazine article, but then not many shops are asking $15k for a pwc. In any case, a test like this would have allowed for comparisons of slalom times as well as peak speed. Lightweight composite hulls are not always an assurance of improved peak speed. It often happens that the race hulls are made with a deeper “V” shape that handles great, but scrubs off speed. The article should have covered this information.

The most surprising part of this entire article are the peak radar speeds. In a nutshell, 61.5 mph is about 6-7 mph too slow for a competitive IJSBA pro tour 785. The GSX R obviously accelerates well, but no 785 race boat accelerates fast enough, or turns well enough, to make up a 6 mph deficit. On top of this, the recreational waterways are full of 62+ mph Sea Doos that could blow by this machine in a long drag race. Our Group K XP super stock II runs 65.5 mph @ 7520 rpm in a stock hull. Even our XP Sleeper (@$650) runs a consistent 62.8 mph. The WPP technicians know, better than anyone, how fast a competitive 785 pro tour race boat has to go. We find it hard to believe that they would offer, for testing, a $15000 machine that only runs 61.5 mph. Particularly when they knew that Polaris would be offering the SLX Pro (which has the same acceleration and speed) at half the price.

This (relatively) low speed begs the question “For what market is this boat built?” Since there won’t be 500 units in time for 1997 homologation, this composite boat is considered a pro modified machine. It cannot be sold to any IJSBA offshore racer, nor novice or expert closed course racers…they are all restricted to super stock boats. IJSBA pros will shy away from the price tag until the speed gets into the 67-70 mph range. There is another viable market that we call “grudge racers”. These are weekend warriors who live to beat their buddies in a drag race…and are willing to pay what ever it takes. Unfortunately, grudge racers usually go for big displacement and long runs (longer than 4 seconds). The only remaining market would be the pwc equivalent of the “hot rod” enthusiast. That is, an affluent and older guy who wants a machine that is built from the best of everything. Yet, like automotive hod rodders, never actually races anybody with it. If this is WPPs marketing strategy…it’s a bold one.

WPP has a very nice website where the information about this machine will no doubt be posted. Our own experiences with pwc customers tells us that potential customers with $15k burning a hole in their pocket will demand the answers to most of the following questions. How does this hull affect peak speed?; Is this the same motor used by the race team?…if not, why?…if so, why is there such a speed difference?; What is the cost breakdown?; Which parts and modifications are available separately?; Will engine packages be available separately?; What is the fuel consumption?; What are the piston and crankshaft replacement intervals of this 7700 rpm engine?; Is any part or the machine warrantied?…what?…for how long?.

The inclusion of this information into the article would have certainly added to it’s readership appeal. Just the same, we look forward to other magazine articles that feature more detailed information about the “race breed” Sea Doo parts and modifications that WPP intends to sell.

Page 48 – Boyesen Reeds on Polaris 780 – This article is not only very informative, but also very well written. Contributor, Heather Selwitz, did an excellent job of giving an abbreviated rundown on how a pwc two stroke works, and why different reeds can make it work better. It seems ironic that a female contributor has accomplished this so much more effectively than many male tech writers have been able to do. In particular, we liked how the acceleration information was broken down into a measurement that every rider understands…boat lengths. We have asked many editors to do this (it’s easy to calculate) as a more real world way to describe speed increases. We applaud Heather’s detail by denoting speeds and acceleration data…but one digit behind the decimal would have read just as well… (relax Heather).

In the past, we have not recommended aftermarket reeds for most models. This recommendation had always been based on back to back (as well as endurance) testing that gave us “lukewarm to disappointing” results. In the past many reed marketers did the bulk of their “testing” by sending samples of their reeds to various race shops, then used testimonials from those shops as their statement of worth. Boyesen has been the first reed company (that we have noticed) that is doing their own definitive “on water” testing to improve and confirm the performance of their product. We had the opportunity to talk with Brian Thibauld earlier this year about the testing he was doing for Boyesen. We were very impressed with both his hands on knowledge, and his commitment to resolve the weaknesses that so many aftermarket reeds have had a reputation for.

This article is a testament to that hard work. A back to back “on water” radar test like this one offers no opportunity to sugar coat the results. Getting genuine acceleration and peak speed increases like this, on a modern high breed pwc engine, does not happen by accident. Granted that the increases are not huge, however they are solid and measurable. Boyesen has taken a quantum leap ahead of all the other reed manufacturers by having the guts to be evaluated in such a test.


No tech items requiring comment.


Page 59 – LA Sleeve – This article carries a lot of good information about a company that is normally very low profile. On Page 60 there are some references to a “Mild” kit and a “Big Bore kit. It would have been nice if these references were more model specific, and gave more price detail. While the big bore kits can certainly increase the displacement by an significant margin, we take issue with the page 60 reference claiming that a 650 can be sleeved and bored to an 850. All the 650 cylinders we have worked with to date (Kawasaki, Yamaha, Tigershark) can “no way” be bored to a reliable 850cc. Just the same, we know that LA Sleeve is capable of high quality work, and look forward to more specific information about their high performance offerings.

Page 72 – XP800 Hop Up – This article is a “more space/fewer participants” version of the Watercraft World performance showcase articles. While this article features wares from fewer shops, the addition of supporting text for each shop is a great idea. This allows each shop to do some background explanation of the intent and features of their modifications. The only problem we have with this article was allowing the shops to eliminate the price limit categories. We believe that performance shops should ignore price tags only after all pwc owners have started to ignore them (we believe that this will not happen any time soon). Stated speeds and rpms would also have given information with a much clearer dollar per mph picture.

In the case of this article, the larger “Sea Doo related” advertisers were featured. While that excludes some of the smaller performance shops, we cannot argue with a publication that offers editorial support to shops that faithfully offer their advertising support. With a reputable editor, their advertising dollars buy occasional editorial “access”…not assured editorial “success”. This article, in particular, showed the best and worst of what can happen.

While all these shops entries lacked specific “on water” rpm and water speed information, Rossier did the best job of giving real world explanations that connected with readers. The RE price list was also the most comprehensive and sensible.

The Westcoast price list was obviously a big screw up on some one’s part. At the very least, it causes one to wonder how many scoop grates and head shells Tom Bonacci’s boat uses. Perhaps WPP will show the corrected chart on their website. We were surprised that WPP chose to waste their editorial space by replaying the same broken record about their race team, rather than offer substantive information about their product. Anyone who has picked up a pwc magazine in the last 18 months has repeatedly read about the massive Sea Doo racing effort put forward by WPP, and the stellar reputation of their head R&D technician, Kel Carruthers. This text was a badly missed opportunity for the marketing folks at WPP to really showcase the fruits of Kel’s work, and tell customers why their parts may work best.

The Factory Pipe text carried plenty of information, but was a little single dimensional. FPP makes exhausts…not modification packages. It would have been nice to see a listing that matched the FPP pipes along with other bolt ons (as was the case in the RE price list). The DCT Sports list was very diversified, but the text gave little background on the specific performance benefits of any of the listed parts.

While this particular article did not come off as well as it could have, we think the concept is great (and worth repeating).


Like many other “boat feature” articles by Riva, this article showcases a machine whose cost is doubled with aftermarket modifications. There is no doubt that this machine is very quick and fast. Riva is correct to target this badly under powered model. We have spoken to many Blaster 2 owners this year who are dead set on making their boat faster…for about $1000. A 9 mph gain is very impressive…but questionably impressive with a price tag increase of $5846. It bears noting that no 785cc Blaster 2 will ever be as fast as an average XP 800. This begs the question whether any value conscious Blaster 2 owner would spend this much for an IJSBA style engine format (for this “apparent” 808cc version). Since there is no point in trying to comply with IJSBA rules, a value conscious person willing to spend $6000 on a Blaster 2 “hot rod” would more likely chose to install an 1100/1200 triple motor. The Blaster 2 engine compartment has enough room to accommodate this engine, and the 1100 pump is already there.

The sidebar on page 68 acknowledges that there may be folks that don’t want to spend $6k right off the bat. This sidebar text gives a less expensive breakdown of the various modifications Riva has for sale. It seems to us that the “average WW reader / potential Riva customer” might have been much better served if the “Deuce” would have been in the sidebar, and the low cost information could have been the main body of this article(with rpms, radar speeds, and engine detail photos that didn’t appear to be taken from the space shuttle).

P.S. By the end of Dec 96 Group K will be posting our Blaster 2 modifications. In short, they are a Sleeper kit (51 mph@$650) and a 92 Hammer (54mph@$1100) No 105 kit is planned.

Page 70 – Chopper City SLTX – While we have done no testing with the SLTX, the modifications outlined in this article seem like a very cost conscious and effective selection. The performance gains appear to be very significant, and the prices are reasonable. This is the kind of article that Riva should have done.

The only problem we see with this article is the incorrectly numbered acceleration graph. The text on page 74 denotes a stock speed of 53.5 mph, and a modified speed of 58.2 mph. However the acceleration graph on page 72 shows “apparent” peak speeds of 48 mph and 51 mph. As in the Rossier article, in last months issue, we are inclined to believe that the chart is incorrectly drawn. This inconsistency makes it very hard for the reader to give credibility to any of the information on the chart. The WW editors should give this repeated inconsistency some serious attention.


Page 32 – Ski Won’t Start – For as short as this article is, it has a lot of very good information. The only thing we would accent is to have the spark plug caps hooked onto the factory ground posts when spinning over a potentially flooded engine. The fine mist of fuel that may spray out of the spark plug holes is VERY, VERY flammable. We recommend placing a towel over the plug holes to reduce the spray somewhat.

Page 44 – It is our policy to not comment on the information in articles about our products. However we feel it is appropriate to add an addendum for new development that has taken place since then. At the time we met Splash editors for this article (June 96), the only Factory Pipe exhaust systems that were available, were Spec 1 prototypes (in the photo on page 45). This pipe works great, but we later felt that it revved a little too high for a recreational type format. We have since switched to a slightly modified stock pipe that nets the same speeds by turning the taller pitched Solas Xo prop to 7230 rpm. For our higher revving full race engine packages, we use the FPP Spec 2 pipe ( it allows 7500 rpm with the Xo prop). For more information about these up dates, see our Sea Doo documents on menu c of the title page.

P.S. The rider weight for all the radar passes in the article was 200 lbs.

Page 70 – Rossier HX 785 – There seems no doubt that RE is capable of building some very fast HX race machines. The 59.5 stated in this article is very realistic…and very fast. Unfortunately this machine is a full modified that, for many reasons, will not be legal for use in the newly popularized (and more affordable) Super Stock class. We are surprised that RE and the Splash editors chose, at this time, to feature a machine that most folks won’t be able to race in 1997. Preparing competitive HXs that will comply with the new SS rules is a huge market that has gotten little to no coverage.

The speed and rpm information presented is very comprehensive, however the rider weight and weather conditions were not denoted anywhere. It would have also been nice if the price list showed the impeller pitch (not stated anywhere) and gave individual prices for all the items listed on page 72. It would give the reader a clearer idea of how $9215 got spent on a $5500 boat.

PWI — March 97

Page 14 – Pro Tec Limited Super Jet – All the tech information and performance numbers in this article seem to be well covered and believable. However a few details seemed a little out of place on this particular machine. “Limited” normally infers a low cost recreational machine…however this Super Jet included, what we considered, some “price” choices.

Foremost of these choices is the dual 46 carbs. While we do not build stroker Yamahas, we have often been told that these 46’s will out perform any other carb on a stroker…that’s understandable. However we question how much of an increase these same 46 carbs can offer (over dual 38’s) on a limited 701cc format machine. Particularly since they contribute so heavily (about 40%) to the $2671 price tag total.

Another expensive accessory is the “girdle” kit. Here again, this is an item used (for good reason) on many modified engines. It just seems like a little overkill for a 701cc limited.

Last, but not least, is the choice to choose race gas compression. The PWI editors should be wary enough to know that pump gas compatibility is one of the primary goals of most limited boat owners. If limited owners were rich enough to run race gas…they would build a modified. In truth, we suspect that lower compression would not have hurt the performance of this boat by much…but the editors should have realized that.

Page 20 – Fischetti Race Boat – What this machine lacks in looks…it makes up for in acceleration curve. For all the ribbing that Fischetti takes for the “rough” appearance of his machines…he doesn’t care because this boat obviously “delivers the news”.

The photography was nice enough, but some better detail of the engine (compartment) would have been nice. The engine photo on page 22 is much like having a picture of a baywatch babe dressed in a moo-moo. An ironic analogy considering that a Factory Pipe is doing most of the covering up.

Page 42 – ADA Sea Doo head – It’s hard to say if this article is intended to be about installing the ADA head (a nice looking but not particularly popular part), or the installation of any aftermarket head. In any case, this article does a good job of covering a head installation in detail. It might also have been nice if the photography showed (potential buyers) the water jacketing of this head.

While the information block on page 44 had lots of nice information, there were several fundamental omissions. No part of this article offered the comparative ADA vs stock water jacket volumes (in cc’s), the temperature reductions that might be expected over stock, the exact performance differences of the new water routing format, and the exact “on water” performance increase. We believe that this information might have better served the readers and potential ADA customers. We think that readers are entitled to some more definitive information when they are being asked to consider spending $352 instead of $40 (to mill the stock head). We acknowledge that the changeable dome design is a great idea for some owners. Those who want to quickly compensate for lost compression at high altitude ride spots, and racers who want to switch between a low compression pump gas format and a high compression race gas format for the weekend. We are surprised that this was not mentioned anywhere in the text.

We agree with ADA that 43cc domes are a smart overall choice for most stock motors. However every “on water” test that we have conducted with 41cc and smaller domes resulted in a loss of peak rpm. If the ADA cooling format some how abates this loss, it would have been nice to outline the exact on water rpm changes. We consider the 39cc and 36cc domes to be a poor (excessive compression) choice for any Rave motor, regardless of fuel octane.

The only serious omission we saw in the installation text was related to the headpipe gasket. This gasket, supplied by ADA, is different from the stocker in that it has no water jacket passage openings. A gasket like this MUST be used when changing to the ADA plumbing format. If a stock gasket is accidentally installed sometime down the road, the results would be a nearly non functional cooling system. This installation text should have strongly accented the importance of having this special gasket (and a spare in your tool box).

Splash – March 97

No tech items requiring comment.

Watercraft World – March 97

Watercraft World – April 97 – Dream Demo Issue – This year’s Dream demo is a quantum leap of improvement over previous dream demo issues. While the radar charts don’t offer exact speed information, they offer a clear and vivid comparison of peak speed abilities. We are also impressed with the choice to compression check each machine, as well as detail which machines are (and are not) pre production prototypes. These are trends that the other publications should match immediately (where they are forced to test pre-pros).

Page 54 – There has been much speculation about the true performance of the SLX Pro 785. The performance claims for this model by Polaris have been bold, to say the least. From everything we can gather about the performance of the production versions of this machine…those claims are true. We are in no way surprised that the dream demo testers loved the performance of the pro 785. However we think that the WW editors omitted one huge factor in the testing of this (and all other) ’97 craft that would have greatly changed the complexion of the results…fuel consumption and fuel range. The comments on page 54 are obviously the comments of riders who were “spoon fed” a “ride ready” machine at all times. It doesn’t require a rocket scientist to figure out that a high breed engine with triple 44’s won’t go far on 9.8 gallons (the smallest tank in it’s class) It’s our guess that none of these test riders had to spend a weekend feeding the Pro 785 enough gas to go on longer rides with folks on other high performance boats. We think that fuel consumption and fuel range information is by far the most glaring information omission in this test (as well as the tests done by all the other publications). The “fuel range” complexion of the SLX pro 785 will very likely be the most extreme example of how pivotal that information is.

Page 64 – We are surprised to see how many publications (WW included) continue to repeat the error of denoting the GSX limited stroke as 68mm…it’s 78.2mm.

Page 80 – Head to Head Test – We wonder how on earth the 1000cc Daytona was considered an even match to be entered in this test…where was the 770?

Page 91 – Compression Tests – We think it’s unfortunate that WW was supplied an obvious “high compression” ringer Blaster 2 for the DD. At least the WW editors had the guts to say so.

Page 106 – Ocean Pro ZXi 900 – The apparent out set of this article was to showcase the performance merits of OP bolt on products for the ZXi 900. However the presentation of the information is so fragmented, it would be very hard for a reader to distinguish how much performance your getting, for how much money, from which part. The editors apparently had a radar gun on site to gauge the results. It seems very silly that they did not make stock vs modified back to back runs. These parts are so easy to install on site, such a comparison would have been easy. Parts like these are not normally expected to make a night and day difference. It is tough (if not impossible) to make accurate comparisons based on tests “done earlier in similar conditions”. The graph on page 108 does offer a very visual example of the results, but a more standard acceleration graph should have been used. We can only assume that OP had taken a radar graph earlier to generate the information for this graph.

The text of the article seemed pretty straight forward, however we have some major disagreements with a few technical points. Page 109 states that the spiral cut head dome pattern puts the mixture into a swirl motion. While we have seen other shops that have mimicked this same feature, there is no test data ever produced by any reputable engine builder/designer that confirms that any such “swirl effect” helps or even exits. No one has ever proven that such a dome shape actually induces a swirl motion on to the mixture, nor that such a motion does actually net a performance benefit…”it simply LOOKS like it ought to work”. Sharp edges, like the ones that exist in the OP spiral domes, are avoided by most engine builders because they are such a high risk starting point for pre ignition. The disadvantages of these shape edges is only one of the reasons that spiral cuts like this are not employed in any true racing engine designs. If OP has definitive, repeatable, test data that proves this design does have performance merits over standard hemispherical domes in high output pwc engines…they ought to present it for publication. Such a tech item would be a first.

Page 111 states that the engine was set up to operate at 180 psi indicated compression. Having done more development with the ZXi 900 than nearly any other performance shop (OP included) we can firmly say that our testing consistently showed 180 psi is way too much compression for this engine. We (and everybody else we know of that worked on the 900 engines) found that the 150 – 160 psi range was always the 92 octane optimum. In all our tests, compression in the 180 psi range yielded excessive heat and reduced peak rpms.

SPLASH – April 97

Observation – We would like to commend the Splash staff for recognizing and printing the demographics shown on page 8. The profile outlined in this page describes 90% of the people who call us on a daily basis. We are encouraged to see the Splash staff recognizes that this is the “person” that their articles should be directed towards. We will be the first ones to tell the Splash staff that this type of reader is usually an accomplished professional that has the experience to ask very educated questions…and expects very concise answers. He (or she) has lots of experience sorting the bs from the “real stuff”. The Splash editors obviously know who to aim the “real stuff” towards. In following entries of this document we will refer to these readers the 41/95 riders (41 yrs/$95k)…we think that talking and writing on their level is fundamentally important.

Page 30 – Westcoast Shop Tour – Shop tour articles about WPP have become pretty common fare in all the publications. WPP obviously has a very nice building with lots of very nice machines in it. Their mass production manufacturing capabilities are easily the best in the business…but none of this is real “news”. What “is” real news is the photo, on page 34, of the WPP pipe for a Laydown Rave engine. The LR 785 pipe market is the biggest, and most hotly contested, exhaust pipe market in the entire pwc business. We suspect that there is more reader interest in this single photo than the whole rest of the article. Tom Kerker is certainly aware of the market interest in this part. It’s sad that there wasn’t more info about this pipe and it’s design, and a little less of the shop photos that have already appeared in so many other magazines.

Page 42 – Yamaha Exciter – The photography of this article is nice enough, but the text fell far short of offering enough information to compel a 41/95 rider to part with $15,000. No doubt editor Marie Loggia had a lot of fun cruising about with her family in the Exciter. But the rest of the potential buyers out here in the world will never get to test ride one…so we are depending deeply on her numerous detailed observations to know how this very expensive toy justifies it’s price tag…Marie didn’t offer much to those readers.

Last fall we had an Exciter owner bring his boat to our shop to have dual Sleeper kits installed on it. This 41/95 guy had lots of big boat experience before buying his Exciter. He said he was impressed with the way it turned, and the high speed rough water stability. His only complaint was that it laid down a little when he whipped it into a high speed turn. We never rode it stock ourselves, but we drove it plenty during our break in and carb tuning tests. All our (pro pwc racer) test riders agreed that this boat pulled more lateral Gs than anything else they had ever ridden in. At 55 mph you could whip the wheel to full lock, and the hull turned like it was on rails. The Gs could literally suck the sunglasses right off your head, and fling them away (we lost several pairs). You didn’t dare grab for your glasses…cause you were hanging on for dear life. In every sense of the word, our Sleeper Exciter was like riding an XP 800 that held 5 people…only the Exciter turns better than most XP’s.

One down side of the Exciter was the uneven engine rpms while straight line cruising. That is, the left engine easily runs up against the 7050 rev limiter, while the right motor seems normally loaded to a lower rpm. We believe this phenomenon was caused by the way the water entered the angled (not flat to the water surface) scoop grate inlets. The Yamaha solution to the problem was to have separate throttle levers (as pictured on page 44). Once at cruising speed, the left throttle must be backed off (usually 30 – 40%) until the tachometers read the same rpms. It bears noting that identical throttle positions always yielded identical rpms during high speed turning (we have no idea why). The only other down side was the fuel consumption. Contrary to what Marie wrote, the 30 gallon main tank lasts just over an hour during aggressive driving. This figures about right since a normal 1100 triple burns 13 – 14 gallons per hour. However we have to admit, once you get addicted to how this boat turns at high speed…you don’t give a dam how fast it burns gas.

Page 56 – This is the second issue in a row that has shown “so called” professional wake boarders performing tricks with no life vests on. We don’t doubt that all these guys think that they are immortal and incapable of being injured…most drowning victims think the same thing. We are surprised that the Splash editors think it’s stupid for pwc racers to do tricks without pfd’s, but it’s somehow cool when wake boarders do it.

PWI – April 97

Page 14 – Gasoline’s – All the information appears to be current and accurate. At times this article got a little lost in the use of numerous chemical names and technical terms, but it’s very tough to write anything about the technical details of fuels without doing so. Overall this article was well done.

Page 20 – Westcoast XP bolt on’s – This article does a good enough job of detailing the features of the parts and the performance increases that can be expected. Like all the other WPP parts we have seen, the machine work is top drawer. From a user friendliness standpoint, the only part that appears to have a problem is the flame arrestor. The installation of this arrestor is more difficult and complex than any other Sea Doo arrestor on the market. That, by itself, is no big deal for the owner who is planning to install it…and leave it alone. However for the high performance customer that intends to make ongoing and regular jet changes, this arrestor is very impractical. This seems ironic since this arrestor was supposedly developed on the WPP race team machines where quick removal and installation are mandatory features. The installation work for this article was obviously done by a WPP technician that has done it many times, not by editor Paul Carruthers.

From a data standpoint, this article has three glaring inconsistencies. The first is the rpm vs speed relationship of the stock machine. 55.4 mph is a little bit on the slow side for a stock XP. Every stocker we have seen will run at least high 56s, most run middle 57s. However unique weather conditions could easily make a normal XP run a little slow. What weather conditions cannot do, is make a stock XP turn 6950 rpm. We have tach tested dozens of stock XPs. 90% of them turn in the middle 6700s, a few have broken into the 6800s. But no stocker, not even one, has ever turned over 6900 rpm. The combination of this irregularly high rpm number along with the irregularly low water speed number cast a shadow on the credibility on the “stockness” of this XP (or at least the impeller).

While the editor never actually writes that the flame arrestor allowed the engine to turn 7150 rpm, he does infer that by saying that the “stock” 6950 rpm was increased by 200 rpm. At this stage of the PWI test, this XP is supposed to still have the stock ignition in place. We find this strange because the stock rev limiters on every XP we have ever run is between 7030 and 7080. We have never seen any stock XP ignition that could sustain rpms beyond 7100. Normally, the only way a stock ignition module could deliver rpms this high would be if it were re programmed. There are only a handful of Sea Doo service centers around the country that have the hardware/software, and Bombardier authorization, to do this re programming. WPP is one of the centers that is so equipped. We can only imagine that the tach used in this test read exactly 200 rpm high, or the ignition module had been tampered with. In either case, this further harms the believability of the tech info of this article.

The other major inconsistency is the references to head volume and indicated compression. The article states that the stock XP head volume is 47cc (160psi), and the 45cc domes of the WPP head yield an indicated 175 psi. At Group K we cc every stock Sea Doo head before we cut it because they vary somewhat. ALL of the hundreds of stock heads we’ve measured are between 45 – 45.5cc. These measurements are known through out the industry. We have never seen one even close to 47cc, and we have a hard time believing that the WPP technicians ever have either. This 47cc specification might only be accurate if the WPP technicians are including the threaded plug hole as part of their measured volume. We doubt that, since no other WPP head domes are measured in this way. This blatantly wrong head volume information casts even greater doubt on the credibility of this article’s tech information and results. We suspect that these inconsistencies are in house issues that WPP will eventually clear up. But for specification wise Sea Doo owners, they sure do make this article less believable.

OBSERVATION – We know of no motor sports publication anywhere (including Cycle News) that would run the interview of the newly crowned world champion in the last pages of the magazine, and an article of some “more of the same stuff everyone else has” bolt on parts in the front of the magazine. We are surprised to see the PWI editors make this choice.

Watercraft Power – April 97

Page 20 – WPP XP 785 Bolt On’s – By now it seems apparent that WPP has effectively orchestrated an industry wide media blitz to land in most of this months publications. While that’s a great deal for them, the magazines hate it when have been maneuvered into running an article that is similar to an article done in a competing magazine…especially in the same month. Such is the case with the article in this months PWI and this article.

The biggest difference between the PWI article and this one, is that PWI actually made an effort to provide “some” definitive performance data. With few exceptions, this article is little more than artfully rewritten verbiage from the WPP catalog. That’s not a bad thing for XP owners who don’t have a WPP catalog. But it’s not a very effective way to impress sophisticated 41/95 riders with the content of your tech articles. We were a little discouraged to see that this issue’s lead tech article contained no radar/acceleration tests, no on water tachometer readings, no fuel octane recommendations, and no way for the reader to assess exactly how much performance he (or she) might expect for $548, $1324, or $1992.

Page 22 states that the one piece head has an enlarged water jacket area to improve cylinder cooling, but gives no data regarding the exact increase in water jacket volume or the actual “on water” temperature reductions that result.

In the Stage 2 text, editor Jimmy Odell infers that the Rotax engine will be able to attain 7500 – 7900 rpm with the installation of the WPP rev limiter…nothing could be farther from the truth. The rev limiter mod WILL NOT increase the rpms of an engine that is not already bumping against the stock 7050 rpm limiter. The prospect of installing this device and suddenly seeing 7500 rpm “on water” is NIL. The best 785 modifieds that exist run in the 7500 – 7600 range. Absolutely no 785 Sea Doo race motor, built by anyone in the world, spins up to 7900 rpm “on water”. Just the same, these boxes can be effective for customers whose engine arrangement “is” bumping the limiter. If you chose to use one of these boxes, we recommend that you first find out what additional fuel octane levels might be needed to contend with the higher operating temperatures.

Perhaps the nicest item in the whole article is the adjustable pump venturi. We are surprised that neither WPP, nor the writer, stated the best size recommendations for the average owner. The stock exit nozzle is 87mm. We think that a 86, 85, 84 diameter set would best serve most owners. We look forward to testing and using this innovative piece. It’s clearly much cheaper than owning three R&D nozzle sets, and probably easier to change at the water to boot. Another very nice (but a little pricey) part is the aluminum exhaust exit. This piece is more for the folks who like to run their exhaust systems “really” dry. Besides being very nicely made, it definitely has a very unique water input format.

Toward the end of the text on page 23, writer Odell refers to the final WPP stage as “this affordable combination”…affordable compared to what? We aren’t sure how affluent the Watercraft Power editors are, but we can tell you that no Sea Doo owners that call us think that $1992 is an affordable bolt on package. We look forward to future articles from Jimmy that have a little more “how much performance for how much money” information.

Page 26 – Lake Cities Polaris 650/750 Bolt On’s – Lake Cities is one of the few shops that has chosen to specialize in Polaris high performance parts, and stuck with it. They are actively involved with the testing and use of these products. Unfortunately, this article tried to cover way too much territory , in way too small a space. Not only is there no radar/acceleration/tachometer information…there isn’t even an individual parts price breakdown. Many parts or packages didn’t even have the price mentioned in the text. While most of these items are aimed at the 650/750 model, there was no mention of which items might apply to the more current, and very popular 780’s. The information offered by this article is barely enough to stir a potential buyer’s interest, much less offer him definitive performance information that might motivate him (or her) to spend money. We look forward to more specific and better detailed articles about Lake Cites products.

Page 30 – Impellers – It would be easy to write volumes about pwc impellers and impeller design. Editor Tom Kerker did a nice job of just covering the basic and introductory info about impellers. It might have been nice if this piece also included some info about the different blade designs and their various abilities…but maybe they planned that for a later issue.

We have absolutely no technical background in the design of impellers, however we do have considerable experience with regards to the different on water abilities of some makes of impellers. Of particular interest to many customers who call us is “exactly what is the difference between “swirl” type props, and the standard blade design props?”. This is an issue that no magazine article has yet covered, so we will briefly try to do so here.

The “swirl” design props (now made exclusively by Skat Trak) offer better rough water “hook up” than any other impeller that we’ve ever seen. With a swirl you can drive right up to the tail end of another machine, at speed, and get the same hook up in his “white water” that you would get on smooth water with a standard prop. This is obviously a huge advantage for closed course racers who are commonly faced with that exact situation. Along with all this wonderful hook up comes one primary disadvantage … peak speed ability. That is, for the exact same crankshaft rpm, the swirl will usually offer less “on water” peak speed. For owners riding in surf, or any other kind of big, rough, water…that’s no big deal. However for the smooth water weekend warrior “grudge racers”, that loss in peak speed is unacceptable. Of the standard blade props we have tested, the Solas “Super Camber” series seem to have uncommonly good peak speed abilities. That is, for the same acceleration rate and crankshaft rpm, these props seem to yield better radar numbers by pure virtue of their blade design. We don’t know why…we just know it’s so. These Solas props do not have near the rough water hook up of the swirl props we have tested, but when it comes to props, you usually can’t have it both ways.

We would like to mention pitch numbers. Despite what you might think, all the impeller makers have their own way of measuring and denoting pitch angles…no two are alike. The result of this situation, is that you cannot make effective pitch comparisons or choices based on comparing the numbers of one maker to the pitch numbers of another. This situation is a growing and never ending nightmare for performance shops and engine builders who want nothing more than to tell their customers “exactly” which prop will work on their boat. We often don’t know ourselves, because we can’t figure out how to make the comparisons either. If you want to know why all the prop makers don’t just get together and standardize their measurement process, we urge you to call them…we would like to know too.

Page 34 – Team Toxic Rotary Valves – We have not tested the Toxic composite rotary valve in any of our 785 Laydown rave engines. While we are not very familiar with this part, we are very familiar with the merits (and demerits) of subtle changes to the inlet timing of these engines. We do not doubt that a thicker valve disk might possibly improve the sealing over the inlet ports. However we seriously question whether this increased sealing, along with any inlet timing change, can result in a lasting 2 mph water speed increase. On the 785 Rotax engine, 2 mph is a lot…a whole lot. Most 41/95 readers are impressed by impartial on water test results, not printed claims. This is a claim that no one else in the Sea Doo aftermarket can match. As easy as this part is to change, the WP editors should have done an on water back to back radar test to allow Toxic to prove this very bold claim.


Page 66 – Spark Plugs – This article has lots of good basic information that’s written in a pretty understandable form. The only exception we take to the text is the part (on page 88) about “Interpreting Conditions”. We disagree with the concept that the plug color can indicate the appropriate amount of premix oil. The text goes on to say that “continual lean conditions will cause the crank bearings to lock up. We are not sure where the editors drew this information, but it’s not really correct.

The moving parts of a two cycle engine have different lubrication needs. The lower end bearings wear best with a slow dripping of a heavy viscosity oil, while the piston and rings wear best with a deluge of a lighter viscosity oil. In a situation where the engine were run unusually “lean” on oil, the piston and rings will normally experience scoring, and/or failure, long before any of the crank bearings get close to the point of failure. We know of no spark plug reading technique that can accurately indicate this.

PWI – MAY ’97

Page 14 – Extreme Blaster – This article appears to be a collective show case for aftermarket bolt-on parts for the Wave Blaster 1. All of the parts used to construct this machine have their own good merits. However for the cost conscious Blaster owner, the whole package makes for a very expensive 49 mph machine.

The one technical aspect that we would take issue with is the compression and impeller pitch choices. We believe that the 190+ psi compression readings taken by the editors is completely accurate (for a 35cc head). Compression ratios this high “might” have been okay for the low rpm “surf riding” boats of 3 or 4 years ago. However the heavily oxygenated pump fuels of today will not permit that kind of compression to run reliably in a high performance engine under any circumstances. We suspect that the excessively high compression might have been employed to pull the unusually steep pitched (for this boat) Solas J impeller. Today’s Blaster owners, that plan to run 92 octane pump gas, would be better served to choose a 39cc head along with the milder pitched Solas I impeller. While this combination will rev a little higher than the 35cc/J combination, it will yield acceleration and peak speeds that are at least as good (if not better). The significant reduction in compression will give the 39cc/I combination a much larger margin of safety from overheating and detonation.

Page 84 – Sea Doo Impeller Change – This article does a good job of outlining the step by step process of a Sea Doo impeller change. The many photos are very helpful. The only thing we would add is an amendment to step #14. The oil inside a Sea Doo pump is some of the most vile smelling stuff on earth. Draining the oil out of the pump, is a process that should always be done outdoors (away from the air in your shop that might be inhaled). If done indoors, you will find the stink of the oil to be very “lasting”.

Page 94 – Motor Oil – This article contains plenty of accurate and understandable information about the oils used in two cycle pwc engines. The most noteworthy item is on page 95, referring to certain brands of oil being required to maintain a warranty intact. This question is most often asked by Sea Doo owners, whose dealers have inferred that if anything other than the “very pricey” Sea Doo brand oil is used…the warranty is void. We are glad that PWI correctly stated that this practice is misleading …”and illegal”.


Page 159 – XP 800 MRD Fuel Injection – In a nut shell this article outlines a full 2 mph speed increase, along with a considerable acceleration increase, by installing a $750 MRD fuel injection system on to an otherwise stock XP 800. As we have said before, a 2 mph gain on an XP is a lot. The $750 price tag puts the MRD system on a par with the popular “oversized” carbs (Buckshot, Red Top, etc). However $750, spent with any one of several aftermarket shops, can easily buy much more than 2 mph. We suspect that the performance increase might be larger on a more heavily modified engine. However aftermarket customers (and magazine editors) are becoming more and more interested in “every day” boat setups…not just full out racers.

We have had many customers use the MRD systems on engines we had prepared for them. While most of them loved the power, most of them also complained of the temperamental tuning and heavy fuel consumption. We are made to understand that MRD has been working to resolve these two long standing difficulties. Failing to discuss (or evaluate) the tuning and fuel consumption issues in this article is a badly missed opportunity for both MRD and the Water Craft World editors.

Page 160 carries a paragraph titled “the trouble with carburetors”. In that paragraph Dave Harryman correctly states that “fuel won’t be delivered until air speed comes up and a vacuum is created”. We agree…and to that end we believe that maintaining the highest possible air speed is a top priority. Excessively large carb throats are often to blame for a significant loss in air speed that results in “less than ideal” low speed response. There can be no doubt about the additional cfm abilities of the MRD system (as well as other 46mm systems) over the stock 40mm carbs. However, we would point out that the port openings in the XP 800 crankcase are only 40mm in diameter. We question how much addition cfm these 46mm arrangements can put through the 40mm case ports, compared to a 40mm carb. One thing is sure. A 40mm throat can have “much” higher inlet tract air speed” than a 46 of any design. That added air speed may not make up the entire performance gap between a 40mm carb, and 46mm fuel injection. However the big difference in fuel consumption could make what ever gap there is, seem much less attractive to many XP owners.


Page 34 – It is our policy to not comment on tech articles about Group K modifications.

Page 48 – Top End Buyers Guide – This article shows photos and prices of many very nicely made top end components. It has been our experience that the customers, getting ready to spend the big bucks to get one of these top ends, are people who have “a lot” of questions…and rightfully so! While this article had lots of nice pictures, it carries no specific tech information that would help a potential customer to make an intelligent buying decision. The article is a great idea that just needs more info to be meaningful to readers.

Page 60 – XP 800 Bolt On’s – This is another article focusing on “bolt on” parts for the most popular aftermarket performance platform…the 782cc Sea Doo Laydown rave. All of the parts featured in this article are well made parts, however the text lacked some detail information about them. Perhaps the most important omission was that of before and after tachometer numbers. Along with this, there is no mention of any impeller or nozzle changes (it would be very uncommon for any XP owner to use this engine setup with the stock prop and nozzles).

There is an unspoken assumption that this bolt on set is pump gas compatible, however we would consider that a stretch. The LR motor, equipped with the FPP spec 1 pipe, normally delivers it’s best results when propped down to allow 7300 – 7400 rpms. Unfortunately that rpm peak (in our on water testing) is very questionably safe for extended high rpm use on 92 octane pump gas. Whatever this machine actually revved during the magazine test, it would deliver it’s best at 7300+ revs.

This article also brings up flow bench comparisons of the carbs for this specific engine. As we mentioned elsewhere, the crankcase inlet port openings are only 40mm. We think it would be very relevant (for readers) to post flow bench tests of the different carbs and manifolds, attached to the crankcase (as they are in the real world). A test of this kind might clarify, for readers, exactly how much additional cfm the engine is really receiving (through the 40mm ports) from the installation of the 44mm carbs.


Page 70 – Super Stock Rules – This is a very well written and researched article. Like all the folks interviewed for this article, we also have a firm opinion about the Super Stock rules (we think they are great for lots of reasons). Despite our opinion, we think it’s great that editor Erin Molholland sought out, and printed, the many different industry perspectives on this subject.

Like all the interviewees, we could list all the politics that supports our opinions. We would gladly take every anti SS argument to task. However, politics aside, we think there are some very important technical issues not covered by the interviewees. Of these, the most fundamental is that of tech inspection. The IJSBA’s first stab at an “affordable” race class was Limited class. It worked great…for awhile. The worst part of the limited class was the close inspection and attention to detail that was required in post race tear downs. Since most competitors suspected each other of cheating…tear downs were common. It often happened that a ,non mechanic, racer would get his (or her) limited race boat prepared at their local dealership. The well meaning shop mechanic (not aware of limited rules) would install an oversized bypass fitting, or aftermarket pistons. During tech teardown, countless riders were DQed for inconsequential detail infractions they knew nothing about. This was particularly distressing when the DQ would take place at a world finals qualifier.

With the exception of Tim Trombly (who supports the SS class), NONE of the interviewees in this article have ever had to be the tech inspector that had to DQ a newby WF qualifier winner because of a 1mm too large bypass outlet. WE HAVE…AND WE HATED IT! After you have to do this a few times, you realize how silly the limited rules are.

When the IJSBA took their second stab at a new “affordable” class of racing, they asked for suggestions. Our suggestion was to make the closest thing as possible to the current Limited class, “that required no detailed tear downs”. This mindset would serve the newbie racers by avoiding “detail DQs” and extensive beachside tear downs. It would also reduce the headaches for race promoters who were wanting an easier tech inspection at the end of the day. We think the IJSBA did a terrific job of meeting these two high priority objectives. For all the performance shop owners that ask “who wants the Super stock class?”…our answer is “the cost conscious racers and the race promoters!!…that’s all” If these shop owners think that limited class was so darn great…let them do all the tech tear downs at the WF qualifiers. It won’t take long to change their tune.


Page 14 – 3 Seater Shootout – Shootout articles are nothing new. However one important part of this article is new . This is the first article, published by any industry magazine, that provides detailed fuel consumption information. The inclusion of this information, in all tests, is long over due. By placing this information so prominently in this test, the PWI editors have obsoleted any other magazine test that doesn’t carry fuel consumption info. Any future magazine test articles that don’t have this kind of information will be “weak”. The other magazines had better get a fuel consumption gauge.

Page 92 – XP limited – Another “XP bolt on” article. Again, these are all nicely made bolt-on parts, but their total cost is a little intimidating. 64 mph is a very respectable speed, however $2200 is alot of money to spend on bolt on motor parts (with prop). There is little doubt that most XP owners would love to have their boat run 64+ mph. But few of those owners (that we talk to) are willing to buy race gas at the rate that an XP can burn it. For a long time the term “bolt-ons” refereed to parts that were able to accommodate the average recreational rider. We are glad the PWI has taken the time to show how that old perception is not necessarily true in all cases. We are also glad to see that this article included information on peak rpm numbers. We agree with the editors comment that this machine might have performed considerably better with the milder pitched Solas X1 prop.


No tech items requiring comment.


Page 28 – Carburetion – This is a well written article that has lots of good, current, information.

Page 40 – Mission Yamaha GP 1200 – Like many readers, we are very anxious to see the performance numbers, fuel consumption rates, and price list for this final machine. We will note that as of this writing, no Solas “K” pitched prop exists for the 1100/1200 pump. The next steepest pitch beyond the “J”, is the “X1”. The X1 is ALOT (not a little) steeper than the J.

Page 48 – R&D bolt on Kawasaki SS 750 – This article appears to be neither a test of a modified Kawasaki SS, nor an evaluation of the R&D parts listed for the SS. While the article does seem to offer some installation information, it doesn’t offer the reader any information that might help to make a more educated buying decision. Page 48 states that “there isn’t much difference between the Xi and the SS”. Editor Mike Koger apparently doesn’t know that the SS has 70 hp, while the Xi has 80 hp. Also the Xi comes with the later style “big pin” motor that has upgraded porting and higher compression. The Xi also has a steeper prop. All this for only $600 more off the showroom floor.

We were surprised that the editors opted to do an article with such expensive bolt-ons for such a mild entry level machine. We agree that most SS owners are soon wanting for more power. However they are most often looking for cost conscious modifications. $1800 in bolt-ons may be effective but it is certainly not cost conscious. We look forward to future modification articles that give some definitive performance information, as well as a cost range that matches the profile of the machine at hand.

Many of the listed R&D parts are a great cost conscious choice for SS owners…although you wouldn’t know from the text offered in this article.

Page 68 – Polaris Reed installation – The detailed photography and text of this article help to greatly simplify an otherwise complex installation. Editor Heather Selwitz did a great job.

Page 76 – Bolt On’s – While this is a great subject for an article, the various categories were covered in such a general way that they couldn’t offer much detailed info. Each one of the “top ten” deserves a detailed article of it’s own.


Page 62 – SMC Plastic Hulls – This is a well written article that explains the advantages of molded plastic hulls for pwc’s. We would like to add one other advantage that was not mentioned…recycling. While the build up of unused hulls in landfills is not a current crisis issue, it will eventually become one. More and more vehicle manufacturers are constructing their products with eventual recycling of their components in mind. We foresee a time, in the not so distant future, when all recreational and competition machinery will be mandated to be constructed from recyclable materials. It makes perfect sense that the aggressive technological pace of racing should be utilized to advance the development of high performance recyclable materials. While carbon-fiber composites are currently experiencing great popularity in all forms of racing, it’s recycling properties (like that of fiberglass) are not good. While we think that carbon fiber is very neat stuff, we also think that it will need to become more environmentally friendly (like SMC)…or become an obsolete material for the 21st century.

Page 138 – Wiseco piston for Sea Doo 785 motors – We don’t often comment on product releases, but this one is worth noting. While the text of this release states that these pistons will use “L” top rings, we are made to understand that only standard ring versions will be manufactured. While this ring arrangement may work okay on recreational boats, it may represent some special setup on racing engines since the use of a standard crown and ring will significantly change the port timing and combustion chamber volume at TDC. Just the same, we think this product has good promise (we have not tested them yet). It may happen the cylinders may need to be modified slightly to obtain optimum results in high out put applications (we don’t see that as being a big deal).

The most notable feature of these pistons is that Wiseco will be offering a .004″ oversize as well as the .010″ and .020″. This slight .004″ oversize will allow 785 Sea Doo owners to lightly hone a pair of scored standard bore cylinders to a nice new finish without exceeding the 785cc IJSBA displacement limit. Currently the IJSBA requires these sea Doo owners to re-sleeve their cylinders back to a standard bore (the .010″ pistons from Sea Doo make the engine 2cc over the legal limit). We think the offering of these .004″ oversize pistons is excellent marketing on Wiseco’s part that will make these pistons very popular among IJSBA competitors.


Page 36 – Flame Arrestor Shootout – We will start out by saying that we have a lot of respect for the editors of Splash for taking on a two part “shoot-out” article that is guaranteed to stir unending controversy among readers and industry manufactures. There will be no end of individuals picking apart the details of this article (us included). However as we often say about our own printed test results “if you don’t like the results, show us a more comprehensively executed test!” The editors of Splash certainly have this same right to say this, and we respect that at this time there is no more comprehensive test.

We are very impressed to see that the editors made the choice to do an on water test to follow up the flow bench tests. We consider the flow bench tests to be amusing…but not important. We have seen countless intake devices that looked great on a flow bench, but lost their luster when tested in the real world. Despite our opinion of flow bench tests, we where very pleased to see that the editors used the wisdom to conduct the tests on carburetors bolted to an actual inlet manifold.

Perhaps the most notable part of the flow test was the Tau Ceti filters. Not because of their flow characteristics, but rather for their construction. The Tau Cetis are the only single mesh arrestor filters in the test (and the only ones we know of). All the other flame arrestor manufacturers certainly have the intelligence and ability to make single screen mesh arrestors…they just can’t get them SAE approved. All these popular arrestor manufacturers are very surprised that a single mesh arrestor can pass the SAE test (we were very surprised too). We contacted Tau Ceti for a copy of their SAE approval paperwork, and they were kind enough to fax it to us. This approval paper work, from a facility in Southern California, appeared to be normal certification paperwork.

Most of the arrestors in the pwc industry are tested and certified by the University of Detroit College of Engineering and Science. These tests (no matter who performs them) are lengthy, and expensive Aftermarket manufacturers have to pay for the testing of their arrestors whether they pass or not. Theoretically, any SAE approved arrestor on the parts shelf of any pwc shop should be able to pass the University’s battery of vibration and flame suppression tests. Shortly after the printing of this article, one of the popular arrestor manufacturers (who has been unsuccessful in getting approval of any single mesh designs) sent an over the counter Tau Ceti arrestor to the University of Detroit for testing. The test was a “no pass”. This test paperwork was then passed on to the IJSBA. With this begins a potentially “sticky wicket” for the IJSBA, who must decide what is legal for racing use…and what is not. Since flame arresting is a fundamental and serious safety issue, we expect this matter will be closely scrutinized by lots of folks before a decision is made. We suspect that, at the worst, the Tau Ceti folks might have been the innocent victims of an incomplete test procedure. One thing is certain…”NO” arrestor can pass a test in California, and then fail the same test in Detroit. We expect to hear more…and write more on this situation as information comes forward.

Aside from all this political hoopla, one other interesting point was the absence of Ocean Pro arrestors in this test. We suspect that OP was invited to participate, and declined. There are probably plenty of good ideological reasons to not participate in such a test, however we think that OP’s absence is not just a disservice to their product, but also a disservice to all the OP customers who placed their faith in the product by buying it. These customers will never know how their arrestors would have measured up in this test. It seems unfair to ask a customer to have greater faith in a product than the maker themselves.

Perhaps the only thing we really didn’t like about this article was the deceiving graph shown on page 47. While the actual flow difference between the Evolution Marine arrestor and the Tau Ceti 3.5i was only 2.5%, the block depicting the Tau Ceti 3.5i is over 900% larger than the block shown for the Evolution Marine…not a very accurate representation. All this said, we still anxiously look forward to next months installment.

Page 100 – Starter Diagnosis – This is a very well written article with lots of good info for the “do-it-yourselfers”. The only thing we would add is that a loose (or broken) ground cable from the battery to the motor is a common culprit in these cases that should always be checked for. In fact broken ground cables on endurance racing Sea Doos are so common that most competitors mount a second cable for insurance.


No tech items requiring comment.


Page 14 – Group K Big Bore Venture – It is our policy to not comment on articles about our product except to offer updated information. Since the outing with the WP editors, we have completely abated the high speed (glass water) instability of our 1130 Ventures with the use of beach house sponsons, and a Jet Dynamics ride plate. Note: Since Jet Dynamics doesn’t yet make a plate for the Venture, we modified and shimmed a Blaster ride plate to fit. We are told the plates will be available shortly.

We should also note that between the photo session and now, the big bore Ventures (with 38 carbs) have become the premiere platform in Region 1 endurance racing. These Ventures are more controllable in high speed, straight line, rough water conditions than any other machine. Add to this that they have a fuel range that is only exceeded by the Sea Doo GSX machines.

Page 16 – Rossier XP Super Stock Kit – Since the Sea Doo 785 platform is, by far, the largest selling driveline platform in the pwc industry, it is the one getting the most attention from the aftermarket. While there have been countess articles about Rossier modified Sea Doos in the various publications, this is the first article about a Rossier 785 Super Stock package. In Super Stock, more than any other class, there is a strong cost vs results mindset among buyers. The total cost of this engine package (with the ECWI) is $2755 as tested. As the text says, the editors specifically were after more low speed performance…that’s okay. The dyno chart supplied for the article by RE Shows a very significant gain in top end power, but a very modest gain in low speed power. This kind of power curve will normally offer “excellent “low end power only when a slightly lower pitch (read higher revving) impeller pitch is used. The 17/23° swirl used in this article is such a prop. While the dyno chart shows the “peak horsepower rpm at 7250”, the text says nothing about the actual on water peak. These boats will often over run the HP peak by 100 rpm or more. This is not an issue for ride-ability, however it can certainly be a pivotal issue for long term reliability (a major concern for most SS owners).

We would have expected that if the focus of this package was “low end acceleration”, the editors would have shown STATS radar graphs that could clearly depict the improvements for the reader. As easy as a head dome change is, it would have also been informative to show the acceleration difference between the race gas and pump gas domes.

It is reasonable to assume that the dyno chart shown in the article is from the kit that uses the race gas compression. The text states that pump gas cylinder head domes are available but you need to be “willing to sacrifice the extra power of the higher compression domes”. It might have also been nice if that pump gas dyno curve was included so that the reader could get a visual idea of the power difference of the different compression ratios.

We will certainly concede that the Skat Trak swirl prop used in this test offers a terrific hook up advantage that comes along with a measurable loss of peak radar speeds (over some other props). Just the same, 62.8 mph XP 800s are nothing special nowadays. We can also say, from personal experience, that anyone who spends $2700 to make their XP go fast is excepting to got lots faster that 62.8 mph…especially if they are being forced to run expensive race gas. Having a “92 octane safe” 62.8 mph closed course XP would be a good achievement. Our Sleeper XP ran exactly that same speed on the same part of Lake Havasu on 92 octane (see Splash Feb ’97). We will grant that our XP Sleeper (@$650) might not accelerate as hard as this RE Super Stock machine, but most readers will certainly have cause to wonder if that acceleration rate is worth the extra cost of bolt on parts and race gas. For the average racer, there would be no question that the extra costs could be worth it. However for the growing number of grudge racers and weekend warriors, all that extra cost will need to buy more than just acceleration.

Page 26 – High Performance Carburetion – Herb Kane is probably one of the best qualified Mikuni watercraft carb experts in the country. This article is well written and informative, however some of the text was a little too technical for the average pwc owner to grasp. Just the same, it’s great stuff for tinkerers.

Page 30 – Riva GP 1200 Super Stock – Like so many other articles done with Riva, there seems to be an assumption that the average high performance pwc owner is ready to spend $5000+ to make his or her craft go fast. Perhaps this is the case with Riva’s customers. If so, we envy them. The average GP 1200 owners that we talk to are understandably in that “$1000 or less” mood.

As always, the materials and manufacturing of the various Riva products is top notch. 65.3 mph is very fast for a GP1200. However like the previous RE 785 Sea Doo article, the boat tested is a race gas only machine. When your talking about a machine with triple 46mm carbs, race gas goes at a record pace (usually about 14 gallons per hour). Our pump gas Sleeper kit for the GP 1200 (@$850 plus prop) can run within 1 mph of this machine. Here again, if this boat delivered the same performance on 92 octane pump gas, it would certainly attract a lot more readers. It’s also possible that a comparative STATS acceleration graph might have given a more visible justification for the costs involved. We are surprised that the WP editors didn’t think that $5800 worth of modifications merited a STATS acceleration test.

While this machine is certainly made up from a collection of very nicely made parts, we would question whether any WP readers have much interest in a $13,760 boat that burns gasoline at the rate of $60 per hour, and only runs 65 mph.

Page 60 – Handling Tricks and Tips – This is an informative and well written article. The only thing we would add is that many of the components that enhance handling will also reduce peak water speed. Of these the most extreme cases are plates and grates for the ZXi 900/1100. Ride plates that reduce the porpoising of these hulls, do so by driving the nose downward into the water. This extra water contact area can commonly cause peak speed losses between 2 – 6 mph…that’s right 6 mph. We have seen NO ride plate or scoop grate for either the 900 or 1100 that does not cause a significant loss of peak speed.


Page 52 – Detonation – The author of this article, Kevin Cameron, is by far the best two cycle tech writer in America. His experience and field of knowledge is second to none. We are surprised and impressed that PWI got him to produce a technical piece for a pwc publication (he usually writes for motorcycle and snow mobile mags). If PWI is able to maintain the services of Mr. Cameron, his articles will be a high quality feather in their cap (that no other magazine will be able to match).

With respect to the text, it is well written and understandable (in standard Cameron style). For us, the most important segment of the whole article was item #5 in the sidebar of page 52. In a nutshell it says that intelligently modified engines are able to complete the act of combustion in a shorter length of time. If this happens, ignition timing can then be retarded (without any loss in power). This is a point that we struggle constantly to explain to our customers. The pwc aftermarket is bustling with ignition components that “advance” ignition timing. Part of the reason these products exist is simply the words “advance” and “retard” that are perceived to describe the direction of power you might get. Nothing could be further from the truth. As we have said before in other technical text…”the best ignition setting is “always” the most retarded timing that still allows for good low range performance”. We urge anyone in the market for (92 octane compatible) ignition components to be very leery of any component that claims to improve performance by advancing any part of your ignition curve.

Advancing ignition timing was a very common (and effective) modification for the very popular ’86 and later Kawasaki 550’s. From this experience, many owners of more current pwc’s have the impression that advancing the ignition timing on current pwc’s will yield a similar result. They are only half right. Advancing the timing on some current pwc models may offer a noticeable increase in low range acceleration. However that gain will almost always come along with a serious temperature problem during sustained full throttle passes. This temperature problem was never an issue on the old stand ups because no one could hold a fast one wide open for 10 – 15 minutes straight. Full throttle runs this long are commonplace for today’s runabouts. Advancing ignition timing is very poor place to go when your looking for extra power. It is a short term quick fix that usually comes with lots of expensive “luggage”.

Page 132 – New K&N Flame Arrestor – We never thought it would happen. After no less than a decade of customers complaining about the fabric element in K&N arrestors choking engines when it gets wet…after everyone in the entire aftermarket has made mesh screen arrestors that don’t choke off air in the wet…K&N has released a mesh arrestor. We commend K&N for the may years that their arrestors were the standard, but their marketing department waited way too long to come up with this (idea?).


Page 84 – Flame Arrestor Test Part 2 – Here again we would like to commend the editors of Splash for taking on a monumental amount of work. We can say from experience that this type of testing is both tedious and very lengthy.

As we wrote for part 1, everyone will be doing their best to pick this data apart (us included). Perhaps the biggest foothold that critics of this article will have is , “all this testing was done at 4000 ft…while less than 5% of pwc riding happens at altitudes that high”. These critics would be right. Anyone who has operated any kind of high performance vehicle knows that when their vehicle is run at higher elevations, the performance is seriously compromised by the lesser air density at altitude. Theoretically it would be possible to argue that the altitude is no factor in this test because all the arrestors had to show their stuff under the same conditions…maybe…maybe not. While it’s true that the conditions were the same for all the tests, the premise is different. What all the Splash readers wanted to know was “what arrestor will give me the biggest power boost…at my ride spots.

Everyone agrees that 90% of Americas ride spots are below 1500 feet sea level. This test, done at 4000 feet, was performed on an engine that was operating in a state of relative oxygen deficit. The data in this test certainly shows how much of that lost power can be reclaimed by various flame arrestors. However we, like many others, wonder if these test results would repeat in a more oxygen rich atmosphere of 1500 feet or less. We are certain that these test were done in the best faith, and with the best of intentions. It’s unfortunate that the circumstances of the venue casts a shadow of question on these results.

There are three other details we would have liked to have seen covered here as well . First, and foremost, is peak rpm. The GSX has a very precise digital tach that could have been used to give definitive peak rpm readings (this is a pivotal piece of data in our flame arrestor tests). The other two points are a reference to the existence of a carb brace, and the ease of carb adjustment with the arrestor and brace in place. Long time owners of Sea Doo engine are aware of how fragile the rotary valve cover/ inlet manifold can be. Any flame arrestor that fits a Laydown Rave motor “must” have a support to the exhaust manifold to ease the strain that will break the inlet manifold. Many of these arrestors have no brace. We consider a no brace arrangement to be unacceptable on these engines (no matter how light the arrestor is claimed to be). Some of the arrestors do have optional “afterthought” braces, however many of those will block access to the high speed adjustment screws (if the arrestor itself doesn’t already do so). These are all important tidbits of information that we look forward to seeing in Splash’s next shoot-out article.


No tech items requiring comment.


OBSERVATION – This relatively new publication has been struggling though it’s first few issues (during 1997) to get itself a personality. This issue is the first, that we have seen, that truly shows the personality that separates WCP from the other magazines. WCP is establishing itself as a “nuts and bolts” type of publication that is aimed at the “do it yourself” type of pwc enthusiast. This is a niche that the other magazines have touched on, but not embraced. This type of format has served Peterson Publications (the parent company) very well in many other mechanical enthusiast industries. If this is a niche that readers are after…they have the corner on it.

Page 18 – Super stock Buyers Guide – While this article carries a lot of good information, it’s far too general to help readers to make an educated buying decision. The price lists could have (should have) shown itemized pricing rather than huge price “ranges”. The editors might have also chosen to do such an article on one particular engine platform per issue, instead of trying to lump them all together.

Page 24 – Pro Tec Super Stock Super Jet – While Pro Tec certainly has a long standing reputation as Yamaha race engine builders, this article is among the first to portray their “Super stock” class engine packages. One of the primary objectives of the Super stock class is to make pwc racing (and the preparation of race boats) more affordable. The 10 mph increase in speed offered by these Pro Tec modifications is certainly impressive, but the $4400 price tag is everything but affordable. Perhaps the biggest over expenditure we saw on the price list was the $1020 carb kit. While 46s may be a benefit on a heavily modified stroker engine, we would certainly question how much actual horsepower benefit they offer over the stock carbs in the S/S type engine. We have seen the stock dual 38 carbs work great for many SJ/SS owners. At Group K we offer a boring and jetting upgrade for the stock carbs that costs only $260.

We were also confused by the cost breakdown of the top end mods. The oversize cylinder sleeves, piston assemblies boring, sleeving, and porting are all shown as separate costs…but suspect that they must all be done together. This makes the total cost of cylinder preparation $940 with no top gasket set. We were surprised to see that case boring (which must normally be done to accommodate the larger cylinder sleeves) appeared nowhere on the price list. The cylinder head (with girdle) is another $340. This $1280 price tag (without gaskets and case boring)) might have been more meaningful to the reader who is contemplating the 753cc big bore top end upgrade. The buyer should understand that while all these mods are prices separately, they are normally sold only as a package.

One other cost that we felt was questionable was the crank true and welding. While this procedure is considered mandatory on most high out put Yamaha triples, we have commonly run our 771cc (85.5mm) Super stock engines trouble free with the very durable un-welded stock crankshafts. The truing and welding is nice, but questionably mandatory for a stand up machine.

We were pleased that the WCP editors printed the true “STATS” radar curve that shows the true peak speed variations that take place while a rider is trying to “settle down” the hull to attain the true peak radar reading. The last 4 seconds of the radar graph show a skilled rider hard at work.

The cylinder head photo on the bottom right of page 25 shows a very noteworthy photo of the first Pro Tec head we have seen without an “O” ring groove. We have never had any success getting the “O” type heads to maintain a lasting seal on any of the large bore Yamaha engines. We are glad to see that the Pro Tec Super stock heads are reverting back to a standard gasket design.

Perhaps the most important part of this article was outlined on page 26, where the editors decided to reschedule their “on water” tests to another day because they had crummy weather on the first (scheduled) day. Like many other after market shops, we have been the unfortunate victims of incredibly bad water/weather conditions on the day that magazine editors intended to do their testing. More than once, magazine editors were unwilling to reschedule the on water tests to get the most accurate possible performance information because it didn’t fit their schedule. We commend editors, like these, who go the extra yard to give the machine an accurate evaluation, and there by give the reader the best possible information.

Page 28 – Kawasaki 900 Teardown – While this article carries somewhat generic information, it is a great primer for new pwc owners who want to understand the innards of their machine…but don’t want to tear it apart to learn about it. The excellent detail of the photography on these pages allows this article to accomplish it’s goal in a an exceptional way.

Page 34 – Install Sponsons – This article gives good information that helps to make sponson installation a lot less intimidating. By far the most important part of this piece is the first appearance of the “mechanical difficulty” rating at the top left of page 34. This very informative symbol is a standard item in many other Peterson Publication magazines. While this symbol does not appear to be very special, we consider it a very important detail that helps owners know which jobs they might be qualified to tackle, and which ones they’re not.

Page 36 – Spark Plugs – This is another very detailed and well written article. The most important part of this article (in our opinion) is item #6 in the sidebar of page 36. EVERY spark plug should be gapped before being installed into an engine…they are not accurately “pre-gapped”.

Page 40 – Carburetion Part 3 – This third installment of the series written by Herb Kane is very accurate and informative. The most import part of the text is on page 42 that describes the relationship between inlet tract air speed and fuel flow. We have always stressed the importance of tuning inlet systems with a focus on inlet tract air speed…rather than sheer cfm (cubic feet per minute) flow. Excessively large carburetors can pass lots of cfm, but high air velocity (of smaller throat carbs) will deliver the fuel quicker and more efficiently.

Page 54 – Spark Plug Gapping – As we mentioned earlier, we consider correct plug gap to be very important. The tool we use to gap plugs is the circular wedge type shown in the photo at the middle of the page. This tool is cheap, simple, accurate, and nearly indestructible. The other gapping tools shown are typically used by engine builders that have “way” too much time on their hands. We don’t know anyone that uses them in a pwc application.

Page 56 – WPP Composite Hull – While the weight advantage of this hull is considerable (125 lb), we question whether that alone can justify a $7000 price tag (not to mention the labor cost of changing hulls). We are very disappointed that the WCP editors did an article on such an expensive handling component without evaluating any of it’s handling characteristics. Even the “Donald Trumps” of the industry demand to have some definitive performance information before they knock out $7000 for one of their toys. We (like everyone else who wants to know what this hull is “really” worth) look forward to a magazine article about these composite hulls that actually defines the performance qualities that merit the price tag. It’s very likely that this hull could have such merits…but you sure wouldn’t be able to determine that from the patronizing editorial space that’s already been dedicated to glossing over matters of function.

Page 76 – Mission Yamaha GP 1200 part 2 – This second segment is a holdover from the June issue’s part 1. Unfortunately, this segment (like the first) has no price information, no performance data, and little or no technical description of the components used. That makes it very difficult for any reader to make a more informed buying decision than he (or she) might have made before seeing either article. One part that would have certainly merited some technical background (and photography) would have been the Dan Lamey modified carbs. Dan is one of the capable tuners charged with the development and construction of the Team Yamaha/Riva tour race boats. The only carb he makes available, that we know of, is boring 44mm Mikunis to 48mm. While this mod is likely very effective on a race motor, the modification costs and increases in fuel consumption would both be fundamental pieces of information that should have been included here.

Another important technical issue is the rev limiter modification mentioned on page 78. We know of NO engine setup for the GP 1200 that can run over 7000 on 92 octane pump gas. If this machine consumes $5 per gallon race gas anywhere near as fast as our 7300 rpm prototypes, we would rate the fuel consumption of this GP (with triple 48s) to be somewhere between 16 – 18 gallons per hour. We question whether that’s a realistic machine for ANYONE to own. At the very least, it hardly fits the “affordable” category that Super Stock machines are intended to be in.


Page 42 – Compression – This is another very well written item by two-cycle wiz, Kevin Cameron. The two items we considered to be of greatest note were in the bottom of the last column. Kevin writes “Always try retarding the ignition with a compression increase…”All of our testing confirms that this is great advice, however this is exactly backwards from what many high performance pwc shops are marketing. Many shops are selling higher compression heads along with cdi boxes that carry more advanced timing (or a more advanced curve peak). This may work great on big block Chevy’s, but pump gas high out put 2 strokes don’t like it. Particularly in this age of “reformulated” pump gasoline’s that as less “high performance friendly”. We can think of no high performance pwc made in the last 4 years that responds well to additional ignition advance. Our advice is “don’t do it…ever”.

The other notable point is where Kevin writes “(additional piston crown temperature)…and flame path length are two reasons why big bore engines can’t run as much compression as can the small bores.” We have long contended that all our testing on the big bore kits (we make) yield their best results with relatively low compression. Despite this, excessively high compression heads are commonly sold for numerous large bore diameter pwc engines. When increasing the compression on your pwc, remember that it’s easy to generate too much compression.

Page 42 – Miller 1045cc Sea Doo XP – Our best 785cc XP Superstocks ran 67.1 mph. We will certainly concede that getting an XP (of any displacement) to exceed 70 mph is a difficult and commendable piece of work. All the parties involved with this machine obviously spent lots of time testing with a collection of very expensive and exotic parts. The components and workmanship can be nothing less than top notch.

The PWI editors did their typically thorough job of gathering all the information about this machine … performance data, prices, etc. However our biggest question is…ement maintenance (or someone who employs such a person). The price tag (assuming that the 46 carb set is about $1500) is about $12,400. This would assure that the potential owner has lots of discretionary income as well. The only place such a machine could be raced is on the IJSBA pro tour…but those guys don’t “buy” boats…they want them for free.

This XP would have a lot more pizzazz about it if the GSXL 950 didn’t exist. By spring of ’98, 70 mph GSXL’s will be common fare…at a fraction of the cost to construct this machine. Just the same, the article made for some interesting reading.

One item that surprised us was the contact information on page 128. Mel Miller has two very fine shops representing his products here, but he offers no phone number for himself. We think it’s pretty darn bold for “anybody” to command $8600 for a short block and offer nothing more than a “I’ll talk to you when I feel like it” e mail address. We can say from experience, anyone spending $8600 wants to get lots of conversation with “the guy” building the motor.

Splash – September 97

Page 30 – WPP flame arrestor Tech Update (?) – It’s a common occurrence for an editor to print a correction of an inadvertent wording error in a previous issue. The editor’s error in this case did not appear to be a big one…but it appears that WPP treated like a big one. This full color page “correction” appears to point more towards the advertiser’s extreme sensitivity, than it does to the reader’s need to be informed. We will add that the components of the WPP arrestor are very nicely manufactured in every way. However we have never spoken to any WPP arrestor owner that didn’t “totally hate” the use of this nylon cord to retain the velocity stacks in place. This cord often jams in place and deteriorates on the sharper edges of the entry holes. At the very least, this is one of the most unwieldy flame arrestor mounting systems for Sea Doo owners who might want to make frequent jetting changes in a hurry. This “update” only highlights that point.

Page 54 – Compression – It’s ironic that PWI and Splash both carry a compression article in the same months issue. The contrast in the two articles is stark. This article (unlike the PWI piece) focused mainly on the measurement process. The only big omission we noticed was specifying the features of the gauge itself. IT IS IMPERATIVE that the gauge you use has the Schrader air fitting in the threaded tip of the hose (where the spark plug firing electrodes normally are). This design assures more accurate readings. Many automotive gauges have the air fitting in the gauge itself. This would include the entire internal volume of the hose as pert of your combustion chamber volume. While this detail makes for a nominal difference on the reading of a large automotive cylinder, it can easily make for a 20 – 30 psi error on a pwc engine. For more info see our Compression document on Menu B of our intro page.

Page 64 – Neptune XP Limited (Pipe?) – This article is another in the re occurring trend to display the performance merits of a 785 Sea Doo pipe on a limited race boat (rather than an otherwise stock machine). These articles are happening because it’s very difficult to show a big performance increase with a pipe alone on a stock machine. To be sure, the 66 mph speeds posted by this machine are “very” impressive (the best limited numbers we’ve seen). These radar numbers are even more impressive when you consider that they were made in 83% humidity (high humidity usually hurts performance numbers on these engines “a lot”)

However, other than the radar graphs, this article was written in a way that provides little (or no) comparative information that would help a reader to make an educated buying decision. Besides the important omissions of compression, peak rpm, fuel octane, and impeller pitch…there is not a single price…not even a phone number.

Bo Dupriest has lots of experience gathering test data, and a good reputation in racing circles. We are very surprised to see him go to the trouble to do such an important article, and provide so little information to his prospective customers…perhaps that was the editor’s responsibility.


Page 24 – About Modified Carbs – While this article, by Herb Kane, is not the longest in this series, we certainly consider it to be the most important. It bears noting (again) that the G-test machine at Mikuni (used to gather much of this information) is unlike any other machine used by anyone else. It’s unique ability to simulate manifold vacuum and fuel flow makes it far more effective than a conventional flow bench.

The numerous important points of this article begin in the second paragraph where Herb mentions the different drawing numbers of various carburetors. There are many different versions (drawing numbers) for each size of Mikuni carb. All these different versions have “very” different fuel metering ranges and rates. This underlines an on-going problem that we (at Group K) encounter daily. It often happens that the manufactures bring out new models that are essentially last year’s engine with bigger carbs. In many cases, a backyard mechanic will get all the jetting specs out of these new larger OEM carbs so that he can install those same jets into another set of carbs he has on his shelf. What this mechanic is often not aware of is the countless “internal circuitry” differences in these carbs that appear “externally” identical. This scenario has caused countless headaches for owners and shops. The lesson is “the jetting that works in one 44 carb will not necessarily work in all 44 carbs…believe it.

The next most important point is described in the column above the drawings on page 25. In short, it says that while modified (larger) throat carbs can always flow more cfm, they cannot flow fuel at that same rate. The result is carbs that can work well when they are tuned perfectly. However these carbs tend to be much more sensitive to subtle changes in air density (temperature, humidity, barometric pressure, etc) In layman’s terms, these carbs tend to be a lot more temperamental. These difficulties with excessively large venturi carbs are the reason that Group K chooses conservative throat diameter increases for all our kits. We have found that on most pwc engines, the small increases afforded by very large throat carbs will often come along with some large doses of constant tuning difficulties. In very simple terms, Herb explains why this happens.

The final, and most interesting, point in this article is the segment regarding flame arrestors. We are pleased that Herb has put into words the truths that finally make all of our confusing test results make sense. For years we have read the magazine ads that showed reputable engine builders endorsing flame arrestors that consistently yielded “less than optimum” results on our engine kits. We knew these guys wouldn’t lie, but we also knew our own on water tests weren’t lying either. It seems that the more “restrictive” arrestors (as Herb calls them) are an asset on excessively large carbs, making them more tunable. On our Group K engine kits, which usually use more conservative throat diameters, we always got our best results with the larger volume and less restrictive type arrestors. As Herb infers, there are no bad aftermarket arrestors. However there can be an arrestor that does not work very well with the carb throat diameters that you have chosen. All this information begs the obvious question, “isn’t a smaller throat carb with a free breathing arrestor a better technical choice that an oversized throat carb with a restrictive arrestor?” We can’t claim to know the complete answer to this question, but we can say that the smaller throat carb with the less restrictive arrestor “definitely” gets better fuel consumption and definitely requires less “fiddling”. In the test we have conducted on our engine kits, we have yet to see the oversized carbs to provide an ability that the slightly smaller carbs do not posses.

Page 28 – Sea Doo 950 engine – For the latest on our 950 information, see our new Sea Doo document page here.

Page 44 – V6 Jet Boat – This article seems to show that Mercury marine is obviously taking the small jet boat market very seriously. This is a driveline that is apparently destined of other small jet boat manufactures as well. We were very disappointed to see that this article contained no fuel consumption data at all. In the future of small jet boating the primary standards of comparison of the different classes of boats will be horsepower vs. fuel consumption (range). Without this information, no prospective reader/buyer could make an intelligent buying choice. We would have reservations about the fuel “friendliness” of a 2.5 liter two stroke with 3 two barrel carbs.

Page 48 – Tigershark Triple Bolt-On’s – The concept of this article is very good, and fits the profile of what most pwc owners want to know (for their particular machine). Black Magic and Abaco both have good reputations where Tigershark’s are involved…they are a good choice for this segment. The item by item breakdown and installation photography are also nice additions that often don’t appear in of magazines. Unfortunately this article omitted the information that readers want most. That is, on water confirmation of the manufactures performance claims, and editorial impressions of how the feeling of the modified machine differs from stock. If all the parts involved were under $100, it would be no big deal. However with a total price tag of $1538 (using stock carbs), this is not an economical or casual modification set. The one modification that was badly out of place in this article was the $1400/$1600 carb kit. The text includes this as one of the top 7 bolt-on’s, yet the text says that these are intended for engines that have pipes and or porting. The article says nothing about any kind of pipes or porting, leaving a big information gap for the reader.

Page 66 – Thread Repair – “Time-serts” are a great way to fix damages threads, and this article does a good job of showing installation process. We would like to add that the only weakness to time-serts is that they need a significant amount of “parent” metal around them to provide support. We have attempted to use time-serts in the exact application as shown in the photos (the top of a Yamaha 633/701 cylinder). In every case the result is the breaking away of the cylinder casting in the area around the time-sert (thus destroying the cylinder). This happens because the Yamaha cylinders simply don’t have enough parent material in this area to support the torque of the head bolt. We always prefer time-serts to heli-coils for thread repair. However in this particular application, we use only heli-coils…never time-serts.

Page 67 – Squish Clearance Measurement – This is a short, but well detailed article. We would only add that you use a solder wire that is between .060″ and .090″ in diameter. Larger and smaller diameters just don’t work as well.

Page 70 – Land and Sea Dynamometer – We have never used a dyno of this type, however it could probably work effectively for folks that wanted to run a battery of different tests without going to the water. This might be a particular convenience for people who don’t have access to a nearby smooth water test site (that’s a lot of folks). The only problem we have with this arrangement is the admission of water to the exhaust system via the engine. This dyno has a regulator for the water brake itself, but not for the engine.

Today’s exhaust systems generate a lot of their performance by manipulating the water input to the exhaust. A big part of getting this manipulation to work right, is to inject the right amount of water at the prevailing water (pump) pressure that you have at that particular rpm. The water pressure to the cooling system (and exhaust system) is constantly varying with the rpm. To conduct accurate pipe testing, you would have to simulate that changing pressure. At the very least, you would have to know what the maximum pressure was for the purpose of peak rpm tests. Each machine has a different peak pump pressure, and that pressure is changed when higher rpms, or more efficient impellers, are applied. This variable would make the uses of this dyno somewhat limited with respect to the finite testing and evaluation of high performance components (pipes in particular).


Page 36 – Top 5 Engine Enhancements – There are few people on the pwc business with more “hands on ” knowledge than author Tim Norton. All the text is very well written and very understandable. While Tim tried to keep the scope of this article (and the article on page 41) somewhat general, all the photos shown were of 785 Sea Doo mods (primarily Westcoast Performance parts).

The only thing we would add would be considerations for engine modifications that retain pump gas compatibility (which most pwc owners want to keep). Modifications that allow for significant gains in rpm ability (exhaust systems and ignition boxes in particular) can often make for operating temperatures that cannot operate reliably on today’s reformulated pump gasoline’s. We would add that you ask lots of questions (before you buy) about this subject if you intent to keep on using pump gasoline’s only.

PWI – October 97

Page 26 – Air Boxes – While the issue of resonating frequency in the air box may be a more common to today’s snowmobiles than today’s pwc’s, the time is approaching when this will be very important for all watercraft. The flame arrestors and air intakes of pwc’s, 3 or 4 years ago, were relatively primitive. However many later pwc’s are coming with air boxes that employ these principles. Foremost of these are the Kawasaki triples and the new GP 1200. These machines have carefully designed airboxes that employ long stacks over the carburetors. The stacks help to improve inlet tract airspeed to the emulsion tubes of the carbs, while the large “still air space” in the air box assures a supply of air to these stacks. In the case of the GP 1200, aftermarket arrestors have offered only minute increases over the well designed stock unit.

Of particular interest in this article is the concept that the backpressure from one carb can literally “charge” the inlet of the other cylinder(s) with a higher than atmospheric charge. In our on-water tests, we have consistently gotten the best throttle response and carburetion while using aftermarket flame arrestors that have the carbs drawing air from a common area (as the R&D and Ultimate brand arrestors do). We suspect this exceptional response is a result of shared pressurization. The individual pod type filters are certainly convenient for carb adjustment, but they have clearly not offered the crisp low range response of the one-cavity filters (on our Sleeper kits). We believe that the relatively conservative carb throat sizes of our kits (compared to everyone else) may also be playing into this result. When carbs are over sized, they will usually react best with a smaller restrictive arrestor (as pointed out by Herb Kane’s article in the recent Watercraft World).


Page 36 – Ultimate PWC – While this article is not actually about the ultimate pwc, the concept of the article is very good. We suspect that this scenario will be playing out for more and more owners who simply can’t afford to buy a new boat each year. Unfortunately, this article reads more like the machines were built “hypothetically”…not for real. No magazine constructs three boats without taking a single photo of the process. We doubt that any boats were actually built, but the anecdotal information and the various phone numbers in the article are still good information. Perhaps the best possible information would have been to post some on-water performance comparisons against the performance stats of the newer model machines that these projects are intended to compete with. But to do that…the “ultimate boats” would have to exist.

WATERCRAFT POWER – October/November 97

Page 16 – Rossier 970 XP – This information presentation of this article is well done. In particular, this is the first article where the shop was motivated enough to install the similar drivelines in stock and carbon fiber hulls for the purpose of comparative radar tests. However, we were a little surprised by these results. Most carbon hulls are made for very aggressive closed course racing, and so are designed to “push” a lot of water. That is, they ride in a way that maintains lots of water contact at high speed for the sake of improved handling. While this additional water contact is great for high speed handling, it often causes a substantial loss in peak water speed. A loss of only 1.7 mph is not much of a loss (compared to others we have seen). The graph on page 18 apparently has the names of the curves reversed.

The driveline of these XP’s seems to fall into the “money is (nearly) no object” category. For that kind of money (about $6100 for the motor work alone), customers would have every right to expect “money is no object” results. While 66.8 mph is certainly fast, there are plenty of 65+ mph 785’s out there, to say nothing of the 70 mph big bore XP featured in the September 97 issue of PWI. We don’t think that Rossier is expecting to sell such a package to lots of XP owners, but we can say that high performance minded XP owners spending this kind of money will want more than 66 mph. Particularly with the existence of the new 950 Sea Doo models.

We also found it unusual that such an engine (in the stock hull) would be built to run on pump gas. It’s been our experience that anyone spending $6000 on an engine is willing to spend the additional money it takes to buy race gas. It’s not like anyone would plan to use an XP like this to go “touring” on. A 66 mph 970 XP would deliver a punishing ride and a fuel range of 35 – 40 minutes (assuming that the 46 carbs offer the normal 15 – 16 gallons per hour at full throttle).

Page 21 – Mission Yamaha 1370 cc GP – This is the third “Mission Yamaha modified GP1200” feature in the last 6 issues. We don’t doubt that Mission Yamaha spends a lot of time working on these machines…but so do a lot of other shops in the aftermarket. The Watercraft Power editors are apparently very good buddies with the Mission Yamaha owners, or they live down the street from this shop and don’t like driving far from home. Whatever the case, they need to get out more often.

At Group K we have done a great deal of testing with big bore Yamaha triple variations. Boring the 1050cc (akGroup K100) motors to 84mm (1130cc) nets a big improvement in overall performance at a relatively reasonable price (since re-sleeving is not required). However to make the 1100 or 1200 cylinders any larger in displacement, the installation of larger diameter sleeves is required. Fitting the sleeves is easy, but making up for the lost transfer port area that your boring away is not so easy.

We prototyped several 86mm bore 1185cc cylinders for potential use in endurance racing. We chose this diameter because it allowed us to remove very little material from the cylinder block, thus removing a minimum of transfer port area, and it’s a displacement that’s legal for IJSBA racing (the 1340 is not). We tested various port layout arrangements, with 38 and 44 carbs, in GP and Venture hulls. Besides the concerns regarding transfer port area, we were additionally concerned about the stock exhaust pipe’s ability to efficiently eliminate the gases of the larger bores. Throughout all out tests, the 1185 prototypes always had great low range power…but at no time did any of these arrangements offer better peak speeds than our existing 1130s. In most cases the 1185’s were about 50 – 100 rpm shy of what the same arrangement of the 1130s would run. We were able to get slightly better peak speeds from the 1185’s by revving them 7300 – 7400 with a very low pitched prop, however we considered the fuel consumption, and engine temperatures, of those rpms to be unacceptable…really unacceptable. We realized that a well-scavenged 1130 cylinder offered better overall results than a higher revving, poorly scavenged, 1185. We abandoned the 1185 project and removed it from our literature.

The folks at Mission Yamaha have demonstrated a more extreme example of this same experiment. By all rights, this 1370 should have enough torque to pull a very steep pitch prop (like a Solas X1) up to 7000+ rpm for a peak speed in the 68+ range. Unfortunately they learned (as we did) that the lost transfer port area won’t permit that sort of torque (not to mention the stock pipe that didn’t get any improvements). These combined handicaps are likely more damaging to the 1340 than they were to our 1185. The Mission Yamaha technicians are apparently okay with standing behind the crankshaft reliability of these huge 89mm pistons on a 7200+ rpm triple crank in the hands of a recreational rider…we would consider that to be a bit on the “technically risky” side.

While this machine is certainly well crafted, it doesn’t have any unique abilities. The speed can be matched by well-prepared 1130 Yamahas and garden variety GSXL 950’s. However, unlike these machines, the 1340 fuel consumption (with triple 48’s) is likely to be in the stratosphere of 18 – 20 gallons per hour at full throttle.

Page 28 – Test Tank – We were glad to see that editor, John Sullivan, pointed out that the test tank can be used as a valuable testing tool, but not a fine tuning tool. In truth, a test tank can get most stock machines very close to perfect. However as the rpms and power output of a machine are increased, the test tank settings become less reliable. “Tank tuning” can be an excellent setup procedure, but (as John states) the last setting must be done out on the water.

Page 50 – Chopper City Polaris 1050 Bolt On’s – Chopper City has been specializing in Polaris models for some time now. We suspect that their parts can net a good improvement for the SL1050, but you sure can’t tell that from this article. While the photos would certainly be helpful to someone wanting to install these parts, that’s not what most SL1050 owners/readers want to know. What they want, is a reliable and repeatable test of “before and after” performance. Given the SL 1050’s poor reputation for rough water handling, on-water testing of the Chopper City handling parts would have been particularly important information that no magazine has touched on to yet (and owners are anxious to read about).

Unfortunately, this article provides little in the way of “real” information that would help a 1050 owner/reader make a wise buying decision. WP editors should know that $920 is not pocket change for their readers.

Page 54 – Hull Truing – While we don’t do hull truing at Group K, we have seen it produce some surprising results. No publication has done a detailed article about hull truing. This article gives lots of great tips. It would be nice if WP did additional hull truing articles in the future that are more model specific.

PWI – November 97

Page 10 – Radar Guns – Over the past few years we have seen numerous articles in the pwc publications about radar guns and radar speed measurement. Most of them were geared to be editorial “back scratching” to repay a radar supplier for lending the editors some very expensive equipment. This is the first article we have seen that addressed the numerous details that can make the difference between an accurate test, and one that’s not. A radar gun is like any tool. It only works properly when used properly. We commend the editors of PWI for doing a “non-fluff” article of such depth. The other magazines should take note that this is the quality of information that they had the chance to write…and didn’t.

Page 20 – 1998 Sea Doos – While there is much to be commented on with respect to these new machines, we think the most important details are those about the 950 GSXL. The, yet to be released, 1998 950 models will apparently come with pumps, props, carburetion, and porting that differ from the GSXL’s that were sold this year. It’s unclear whether the new pump can be fitted on 97/98 GSXL’s, however it is clear that the introduction of these significant changes will create two types of GSXL’s. The differing port timing will likely result in the need for head volumes of different specification, and so too for the carbs. To avoid any confusion between these models, all our future literature and postings will refer to the current GSXL’s as “grey 98” models, and the new ones as “red 98” models.

Page 28 – Impellers – This is yet another example of the superior writing and research abilities of tech contributor Kevin Cameron. This article, ironically written by someone outside the pwc industry, carries detailed information that has been ignored by all the other magazines that have written weak impeller articles for years. This article is written in understandable language with numerous analogies that help the reader to understand the text. The other publications should take note that this is how a tech article is to be written.

SPLASH – November 97

Page 32 – XP Pipe & Arrestor Bolt On – This article is very well detailed and well written. The only technical data that might have been additionally helpful would have been digital tachometer readings, and the retail prices of the parts. The increase from stock (56 mph) to the final 61 mph is a good overall increase. During our testing with the XP 800, we found the Factory spec 2 pipe and the Ultimate Flame arrestor to be very effective pieces. However in the scheme of “bang for the buck”, these parts would not have been our first choices. A Group K Sleeper kit costs $650 ($520 for the mods & $130 for the R&D arrestor), and nets a solid 62 mph peak speed using the stock ignition and stock pipe. We will concede that the Factory pipe arrangement is likely the next best thing for owners who lack the time element to send their parts off to be modified. Many of our customers have installed aftermarket pipes on to their Sleeper XP to get a significant additional boost that is well beyond the pipe alone (we usually prefer the less expensive Spec 1 with our Sleeper kits).

We have never tested the Spec 2 pipe on a stock machine to know if a different impeller could further enhance the results. However we would be very inclined to recommend such a prop (like a Solas XO or a Skat Trak 17/23°). In pipe tests with our Sleeper kit, these lower pitch props offered much stronger acceleration with slightly better peak speed ability.

Page 38 – Red Top Carbs – The marketing (and magazine coverage) of modified carbs of all sorts is becoming increasingly popular…we think that’s great. What’s not so great is that the manufacturers of these carbs, and the magazine editors, are all acting like these mods have no significant impact on fuel consumption, or that nobody cares about it. We believe that nothing could be farther from the truth. It seems that anyone with the technology to execute these elaborate and expensive modifications to carbs should also have the technology to provide accurate “before & after” fuel consumption information. This is not been common information because the magazine editors don’t ask. We think that hen a carb mod costs $1000, somebody ought to be asking.

The Red Top carbs, that we have seen, appear to be very nicely crafted parts. We have not conducted any on-water tests with these carbs, however we have tested other similarly modified carbs. To be sure, the design of the atomization system could give these carbs some performance abilities that other aftermarket modified carbs might not possess. However even with this, we take some serious issue with the performance numbers from this particular test.

The XP in this article ran 58.6 mph in stock form. We have heard claims of stock XP’s that could run middle 58s, but we have never actually seen one do it (it would require about 6850 rpm…unusually high for a bone stock ’96 XP). This is another case where digital tachometer readings (included in the article) could have spoken volumes about how this “stock” machine might have been able to generate this kind of speed. These same tach numbers would have shown the definitive “on-water” engine rpm increase with the Red Tops.

While the stock numbers of this XP “might” be possible, we question whether the Red Top installed numbers are. Running 61+ mph with a stock prop and nozzle would require the engine to rev almost to the rev limiter at 7050. For “any” XP to spin the stock prop into that range, the port timings would require alteration, or the tuned length of the pipe would need to be changed. After a couple of years testing with these engines, have never seen any exception to that. As good as Red Top carbs might be, no amount of fuel atomization can allow an otherwise stock XP to over-run these specification needs. The very best we have seen any carb set run on a totally stock XP is 6950 (that is with Buckshot 44’s or Group K 40’s).

The GP 1200 numbers represent a different dilemma. The GPs have had a notoriously wide spread of stock peak water speeds (apparently a result of hull variations since they all seem to turn 6800-6850rpm). Stock GPs have ranged from 54 – 58 mph (on glass water). The stock 56 mph GP 1200 in this article is not unusual, however the comparative Red Top average speed of 61.2 is very unusual. Just a few days before this writing, we had occasion to do a battery of radar tests with a 56 mph GP 1200. At 6820 rpm this (stock prop, plate, and grate) GP1200 radared at 56.2 mph. Minutes later, the same machine was radared at 58.7 mph @ 7020 (hard up against the rev limiter). We then installed a steeper Solas “J” impeller (as we mandate for all our GP Sleeper kits) to get 61.1 mph (still against the 7020 rev limiter).

Armed with this on-water information, we consider it to be mathematically impossible for a bone stock, 56 mph, GP 1200 to run 61.2 mph without over-running the rev limiter by a good margin (to roughly 7200 rpm). Here again, as good as Red Tops might be, they cannot increase the pitch of a stock prop, nor eliminate a rev limiter.

In the end, the folks at Red Top will need to answer to their customers for whatever claims they make in the publications…what we think really doesn’t matter. We can, however, say that we believe these performance claims will be tough to match on the pure stock XP and GP machines that we have seen.