– by the Technicians of GROUP K
PREFACE – At Group K, we are inundated with phone calls from prospective high performance buyers/racers, each wanting to know what the “hot setup” boat will be for the that season…and what their prospects are of keeping up with that boat. This document will attempt to address those questions, and give some perspective of the abilities of the more popular high performance machines (as we perceive them).
Along with this information, we will also note the prospects of high performance modification (as we see it), and the possible side affect difficulties that might come along with those modifications.
THE BEST RUNABOUT “SPEED” PLATFORMS – Not everyone wants to have the fastest boat on the lake…but everyone seems to want to know about them. The following list is our opinions of the top setups for peak speed on glass water. All the setups are listed in terms of modification sets we have run. Other performance shops have setups that could fit in this list too, however presenting those setups (and the costs) is their job not ours. All stated speeds are @ 0-500 feet altitude, smooth water. Where modifications are in use, the approximate “cost of modification” (to the engine) is denoted.
105 OCTANE RACE GAS
Cost of Modification
Group K Price
71-72 mph GP1200 105 Hammer kit with FPP pipes
70–71 mph 1130cc WaveRaider 44carbs/stock pipe
67-68 mph ‘97/98 XPL 950 Type 2 kit
67-68 mph 1130cc Type 2 Wave Raider (38 carbs)
66-67 mph ’97 GP1200 Type2 kit (stock pipe)
66-67 mph 785cc SS 2 mod Sea Doo (’96) XP
92 OCTANE PUMP GAS
Cost of Modification
Group K Price
69-70 mph ’98 GP 1200 Hammer kit (w/FPP triple pipes)
66-67 mph ’98 GP1200 with Sleeper kit
64-65 mph ’97 GP1200 with Sleeper kit
63 mph ’98 SLX pro 785
63-64 mph Raider 1100 with 1130cc Big Bore Sleeper
62-63 mph Zxi 1100 with Sleeper kit
62-63 mph (’96) XP Sleeper kit
62-63 mph ’97/98 SLX 1050
62 mph ’98 XP 950
62 mph ’97 GSXL 950
62 mph Aqua Sports “911” (900 made to 1100)
60-61 mph ’98 GP 1200
60-61 mph Sea Doo GSX 785 Sleeper
60-61 mph Sea Doo ‘97XP 785 Sleeper
Performance Runabouts of Choice
Polaris SL 1050 – The ’98 models do, in fact, run 62-63 mph, making this the fastest stock machine on glass water. The ’97 SL was also very fast, but it was notorious for loosing large measures of peak speed (and handling) as the water became anything less than glass. The ’98 machine (supposedly) uses the same bottom, so it shares this same “unfriendly” rough water performance. Given this, these Polaris 2 seater 1050s will be a poor choice for closed course or endurance racing owners. While there are aftermarket bolt ons available for the 1050s, none appeared to make a huge improvement in speed or rough water worthiness of the ’97 1050.
The biggest aftermarket performance prospect for the 1050s is the release of triple pipes (from FPP). While the power increase of these pipes is considerable, the longevity and handling issues will likely require some attention. The only apparent “Achilles heel” of high performance 1050s appears to be the driveline/driveshaft system. For more info on these, see our Polaris 1050 document here.
Polaris SLX Pro 785 – To be sure, this (very expensive) limited production special purpose boat is the fastest (and best rough water handling) in the 785 class…and it can blow off most open boats as well. For closed course racers, this boat is a great choice. However recreational riders, in search of a “fast” stock machine might not find the pro 785 entirely to their liking. The combination of the (somewhat small) 9 gallon tank along with the triple 44 carbs (bigger than average), on an engine that spins 7700+ rpm (higher than any other pwc) makes for a fuel range that is much shorter than most of your riding pals. However this range annoyance is small compared to the actual ” ride” annoyance that the pro 785 delivers in rough water. Granted that the pro 785 hooks up good and does not porpoise in rough water. However it accomplishes this by giving a ride that many riders consider to be “punishing”. That is, the rider “feels” the roughness of the water being covered because the hull holds it’s nose down so well. This type of ride is fine for wiry and athletic riders for the length of a (relatively short) closed course race. However it can get to be “very” abusive for casual recreational riders.
The majority of the aftermarket mods for these boats are geared toward the specific needs of closed course riders. It would be difficult to make this high revving machine run significantly faster without inducing some reliability issues, or the need for expensive race fuel.
Yamaha GP 1200 – Few high performance pwc’s have been “maligned” more, for not performing up to claims, than the ’97 GP 1200. While some owners take numerous issues to task, we will stick to speed performance issues.
Most of the ‘97GP 1200 owner performance complains were justified…but in most cases the fix (aluminum trim tabs) was relatively inexpensive. All the “slow” GPs we worked with were easily resolved in this way. To be sure, Yamaha could have saved themselves lots of grief and lots of unhappy owners if they would have identified and resolved this problem earlier in the season…but they didn’t. In the scheme of numerous high performance boats that have had a “you have to replace this part” scenario…the GP 1200 problem was not very complex, and had a relatively inexpensive fix.
The early ’97 hulls were made thinner than what might have been ideal for this kind of machine. Yamaha offered bracing update sets (that bonded to the inside of the hull) to avoid any cracking. However, the outer hull surface of some of these “braced” hulls could still flex about slightly in a way that ebbed away some peak water speed ability (the thicker ‘98s do not flex in this way). Serious grudge racers, with their heart set on a GP 1200, should probably set their sights on a ’98 version.
That said, the ’98 GP has all the “’97 issues” attended to. Along with that, the ’98 GP has a 5’ angled exit nozzle, and more rigid hull, which contribute to a slight increase in speed. Sleeper ’97 models (with aluminum tabs) will run 64-65 mph on pump gas. The Sleeper ’98 models will run 2 mph faster for the hull thickness and nozzle improvements. Regardless of what the GP 1200 nay Sayers think, either year GP is still one of the top performing grudge racing setups around. Along with that, they will out accelerate virtually anything, and negotiate high-speed turns far better that the GSXL.
When the GP 1200s were released, no one could dispute the excellent turning ability of this hull. They were the first production open class machines that really handled and accelerated well enough for serious closed course racing (they still are). Surprisingly however, the GP hulls didn’t lend themselves very well to endurance racing. At very high speeds (in rough water) the GP hull does a nose-to-tail bouncing that no rider can control (for 60-90 minutes anyway).
With the availability of the FPP triple pipes, GP1200s can easily be made into the supreme horsepower and water speed king of any piece of smooth water. No other modified platform can come close this combination of sheer speed and reliability.
Sea Doo XP 950 – Despite the relatively long hull, the spring seat XP 950 has excellent peak water speed abilities. In our ’97 XP 785 tests, we observed that the longer and heavier spring seat hull could run peak speeds very close to the shorter and lighter ’96 XP. This happens because the spring seat boat lifts so much of it’s hull out of the water during smooth water peak speed runs. This same quality allows casually modified XP 950s to run peak speeds into the high 60’s. We suspect that the speed difference in equally modified XP and GSXL hulled boats will be nominal. Unlike many other hulls that do well on glass water, the XP 950 is at the head of the class in high speed rough water competition. This machine is the only 2 seater that can compete with the fields of modified 3-seaters that otherwise dominated 1998 rough water endurance races.
The closed course abilities of the XP 950 remain to be seen. The closed course weakness is the large amount of water contact area that must be accelerated off of the start and the corners. The increased rider comfort and good cornering hook up of the XP 950 will help to overcome some of this weakness, but there are some pretty quick machines in today’s open class. In addition, if the IJSBA adopts the 0-1200cc ruling, all the open boats may have their hands full dealing with the 785 class boats that they had previously be protected from.
From a performance standpoint, it is very easy (for us at Group K) to net big increases in acceleration and speed from the 950 machines. Unfortunately, it seems that any significant increase in peak rpm can contribute to reliability issues that may be manageable for racers…but are unacceptable for the average recreational user. For more info on these, please refer to our 950 documents on our internet web site.
Sea Doo GSXL 950 – The ’98 GSXL accelerates and hooks up about the same as the ’97 “gray” GSXLs. Both boats share the same (excellent) smooth-water peak speed abilities…and the same high-speed rough water “unfriendliness”. The GSXL is easier (than the XP) for two people to re-mount in rough water…but beyond that we can’t think of any other reason that a high performance rider would want a GSXL over the XP 950…(price maybe?) The “less than ideal” rough water handling of the GSXL will not lend itself very well to endurance (or closed course racing)…particularly with the XP 950 in the picture.
Despite all this, the power potential of the GSXL will easily keep it consistently close to the top of the heap when it comes to smooth water “grudge racing”…particularly in the field of pump gas compatible machines.
Kawasaki Zxi 1100 – The Zxi 1100 is a comfortable recreation machine well suited to smooth water cruising. However this boat doesn’t have any special abilities that qualify it as a top choice in any particular style of competition . The engine and driveline have good reliability and good horsepower potential. Unfortunately the 1100 is still smarting from the “black eye” it suffered when the ’96 models exhibited a “high speed instability” on glass water. The recall update, implemented by Kawasaki to resolve the problem, also caused a significant reduction in peak speed ability. As a result of all these complications, very few high performance shops did serious development with the ZXi. The ’97/98 1100s had the new updated hulls, however the pumps were changed in a way that didn’t permit for the hook up of increased power.
These issues aside, the Zxi 1100 never gained good popularity as a closed course or endurance machine because of a nearly uncontrollable porpoising at high speeds in rough water. This porpoising could be abated with various plates, grates, etc. However the 1100 (more than any other machine we’ve seen) suffered huge losses of smooth-water speed when these parts were applied (5-7 mph losses were common).
As a grudge racer, the Zxi 1100 never became part of the high performance upper crust partly because of the afore mentioned hull issues, and partly because of the excessive weight (compared to other top machines)
Kawasaki ZXi 900 – The little brother of the Zxi 1100 was never considered a “high performance” competition machine. It suffered from the same problems with excessive weight, and serious speed reductions from aftermarket plates and grates (intended to abate the porpoising). This said, there are lots of “good condition” used (read good bargain) 900s out there. More recently, Aqua Sports (in Torrance Ca.) has been converting the (cheap to buy) 900s into 1100s. This modification transforms the docile, slightly overweight, 900 into a low-cost pump gas pocket rocket (62-63 mph). The smaller prop used on the 900s allows for better acceleration than the 1100 motor delivers with the larger 1100 pump. Furthermore, the smaller 900 carbs (if used) yield better fuel consumption than the accelerator pump 1100 carbs. All these mods do not make the 900 good in rough water, but they do elevate the otherwise wimpy 900 into the upper crust of the smooth water grudge racers…at a good price.
Yamaha 1100 Wave Raider – No Wave Raider 1100 owner will argue with you about the “scary” rough water antics that these hulls consistently deliver. This machine has absolutely no prospects of being a competitive (or safe) machine for rough-water endurance or closed course racing. Despite this unfavorable characteristic, the 1100 Raider hull is the king of delivering mph-per-horsepower (on smooth water). At high speed, on glass water, the Raider hull sits almost completely off the water without loosing any hook up ability. For riders that want to build the ultimate glass water grudge racer…the Raider is very hard to beat. Add to this that there are still many “low-hour” used Raiders available at bargain prices. Given the good longevity of the 1100 motors, buying a good-condition used one is usually a safe bet. We expect that these machines will be top notch “drag racers” for some time to come.
The only Achilles heel of the 1100 models is the engine-mounted cdi box. The cdi boxes do not like the high frequency vibration of the triple motor. Yamaha offers a head-to-ignition case brace that reduces the vibration, and helps greatly to avoid the cdi failures. However we finally started mounting the cdi boxes on the (nearby) gas tank to eliminate the problem.
Sea Doo 95XP800/96XP~97/98SPX – While there are several different year and model designations for what is basically the same boat, most industry folks refer to this 785cc boat simply as “the old XP”. No pwc better fits the title of “hot-rod” than the XP. Simply put, no machine matches the XP’s combination of power, handling, and affordability. In stock form, the XP is an easy match for most of the open class machines. However unlike most of the open boats, the XP gains big speed increases for relatively small amounts of modification money. A Sleeper kit and a Rossier pipe will transform the XP into a 64 mph pump gas pocket-rocket that can be king of most local ride spots…at a price that’s easy to live with. Our test riders have often characterized the acceleration and handling of the XP as “the closest thing to riding a modified stand-up”.
The excellent rough water handling ability and horsepower-to-weight ratio of the XP has made it the most dominant machine in closed course racing everywhere. Ironically, while these qualities make the XP ideal for closed course, they can become a curse to endurance racers. The light-weight and short length that work so well in closed course, make for a very “busy” ride at high speeds in rough water. Maintaining control can be done by riders that are very experienced, and very physically fit…but it is full time work.
Since these boats have been around for so long, there are plenty of inexpensive used ones out there. For used XP buyers, we recommend to find a low hours machine. If you’re a tinkerer that enjoys doing your own top to bottom rebuilding, a dirt cheap high hours boat can be a good buy. But if you are not a tinkerer, a high hours machine, no matter how well maintained, will often require maintenance and replacement of perishable parts.
Sea Doo GSX 785 – The GSX 785, in every sense, has abilities that run a split between the ‘96XP and the spring-seat 785. The additional water contact surface area of the larger GSX hull makes for waterspeeds comparable to the larger spring-seat 785. The high speed turning abilities of the GSX are not quite as quick as the ‘96XP, but the GSX hull has a “like it’s on rails” turning ability that allows any riders to make aggressive high speed turns with absolute confidence. Furthermore, this turning stability surpasses the ‘96XP, as water becomes rougher.
The high-speed rough water handling (and hook up) of the GSX is much better than the ‘96XP, but not quite as good as the spring-seat 785. Just the same, the GSX 785 has been the most competitive 785 endurance machine of the ’97 season, where it commonly held it’s own against the top pro open machines. The GSX may not be the ideal smooth water grudge race boat (Sleeper GSXs run 60-61 mph), but in 6-10 chop the GSX 785 can hunt down any other runabout on the water. Perhaps the most unique quality of the GSX is that it offers the most comfortable two-person riding of all the Sea Doo runabouts. We consider that to be a rare quality in a machine that handles this good. The other most attractive quality of the GSX is that it carries 15 gallons of fuel, to the 9 gallons of the ’96 XP and the 11 gallons of the spring seat 785. This is an important quality because the 785 rave motors are thirsty little suckers…ask anybody that owns one.
Many GSX 785 owners traded up to a GSX 950 figuring that they would have the same handling that they had grown to love, along with a big dose of added power. Unfortunately, that high quality handling got lost somewhere in the translation. The GSX 950s have nowhere near the rough water handling and hook up ability of the 785 boats (we have no idea why). It has become common for the GSX 785s to easily overtake 950 GSXLs as the water gets one foot or rougher. If you are a rough water rider…a bigger GSX may not necessarily be better.
Sea Doo ’97 XP – To avoid any confusion between this machine and the other Sea Doo models we refer to it as the spring-seat 785. Like the first Kawasaki 900, this machine won plenty of awards and pre-season hype, but disappointed many buyers with it’s lack of performance. This was a particular disappointment for the Sea Doo faithful, because the spring-seat 785 was the first XP that did not outrun it’s predecessor. The 7inch longer, and 90 pound heavier, spring-seat 785 is actually only 1 mph slower (on smooth water) than the 96 model. It has this good speed ability (for it’s size) because a good majority of the hull is lifted out of the water during straight-line high-speed operation. However when the 97 XP is laid into a hard turn, it has to overcome the considerable drag of it’s additional weight and water contact surface area. All this additional drag, while cornering, is what eliminates the spring-seat 785 as a closed-course racing contender.
All this said, absolutely no existing runabout offers greater comfort or control in high-speed rough water conditions than the 97 XP delivers. These machines are ideally suited for endurance racing and rough water recreational riding. Sleeper modified spring-seat 785s run 60-61 mph on smooth water. But in the rough they can easily hang with the big horsepower boats, and still give the rider a fraction of the physical abuse that everyone else is getting. We consider this machine to be a best buy for riders looking for an affordable endurance machine.
Yamaha GP 800 – The all new engine in this machine is a technological quantum leap from all the previous two cylinder Yamaha pwc engines. The apparent intent of this machine is to give the Sea Doo XP/SPX some competition in the 785cc racing division. With a stock peak speed of 59 mph, the little GP is on it’s way to meeting that objective. However riders considering the GP 800 as a race platform need to take a closer look. To be truly successful, “modified” versions of the GP800 will need to be on a par with the plentiful “modified” versions of the Sea Doo785. Given that the GP800 is 12 inches longer and 70 pounds heavier than the XP…that may be a tall order.
While factory supported GP 800s have done well in national level closed course racing, privateers have struggled with the fleets of fast Sea Doos. As more performance parts and modifications become available for the 800, it will become easier for privateer owners to narrow the gap they face. However building an IJSBA legal superstock 800 that can do battle with the best Sea Doos will be no small piece of work.
Since the GP800 weighs only 30 pounds less than the 1200, there is not much reason to believe that the little GP will handle much better in high-speed endurance racing than the 1200 does. While the closed course abilities remain to be seen, the 800 seems destined to struggle in the horsepower department (for ’98 anyway).
THE THREE SEATERS
Before the 1997 endurance racing season, no one seriously considered 3-seaters as competition machines. However, with few exceptions, all the top levels of endurance racing have now become dominated by 3 seaters. Since the three seater market is the biggest and fastest growing segment of the pwc market, there are plenty of folks out there interested in dabbling in endurance events with their 3-seaters. Our comments for these machines will be specific to that type of competition only. Here is a list of how the smooth water speeds stack up.
110 OCTANE RACE GAS
Cost of Modification
Group K Price
62-63 mph 1130cc Venture 44carbs/stock pipe
60-61 mph 1130cc Type 2 Wave Venture (38 carbs)
92 OCTANE PUMP GAS
Cost of Modification
Group K Price
60-61 mph SLTX 1050 Sleeper kit
59-60 mph ’97 WaveVenture1100 with 1130cc Big Bore Sleeper
58-59 mph STX 1100 Big Bore Sleeper kit
58 mph ’98 GTX 950
57 mph ’97 Venture 1100 with Sleeper kit
57 mph Sea Doo GTX 785 Sleeper
56 mph ’98 Yamaha XL 1200
55 mph ’97/98 SLTX 1050
52 mph ’97/98 STX 1100
52 mph ’97 Wave Venture
52 mph Sea Doo GTX 785
Yamaha Venture 1100 – No 3-seater has had more success in 1997 endurance racing, in the USA, than the Yamaha 3 seaters. Certainly not the fastest of all the 3-seaters (in stock form), the Venture 1100 (like most Yamahas) maintains excellent longevity when modified. But more importantly, the Venture has few (or fewer than the others) side effect failures that result from the heavy abuse of endurance racing.
The 1100 engine lends itself very easily to displacement increases up to 1130cc (same as the XL 1200). Whether the engine is run as a 1050cc or 1130cc, the (relatively) fuel efficient 38 carbs of the Venture still yield excellent acceleration and peak speed abilities. The installation of triple 44s has been a popular modification for some racers. The increase in acceleration of the 44s is considerable, but the increase in peak speed is small. These riders quickly learned that the small increase in peak speed afforded by the 44s comes along with a noticeable increase in fuel consumption.
The primary weaknesses of the Venture are the ignition electrics (as mentioned above for the 1100 Raider) and the drive line coupler. Both of these issues are relatively easy to deal with. The rubber coupler simply requires regular replacement, and the ignition cdi box needs to be mounted off the engine to avoid vibration damage.
Kawasaki STX 1100 – For some time after it’s release, the STX suffered an undeserved reputation as an un-competitive endurance racing platform. A big part of the problem was that modification development by many performance shops was delayed as a result of them shying away from the high speed handling issues of the ZXi 1100. Another part of the problem, in the USA, was related to ignition curves that have been designed to contend with our “reformulated” pump gasoline’s. Our European customers have told us that STX 1100s (with the non-USA ignition curves) are the horsepower kings of European open class endurance racing. We have never seen (or radared) one of these STXs, nor have we ever obtained one of these ignitions to confirm it’s abilities. Since Kawasaki had no official involvement in endurance racing (in the USA) there has been no source for this information, or these parts.
Regardless of what ignition can or cannot be had, we consider the STX 1100 to be the most promising of the endurance racing platforms. All our work, to date, with the 1100 Kawasaki engine has shown it to be easily as reliable and durable as the Yamaha. In addition, with very little work, these 3-seaters can be made to handle, AND TURN, excellent.
Polaris SLTX 1050 – Owners of stock Polaris SLTXs have had outstanding reliability, and outstanding race results, in the amateur levels of endurance racing. While the ’97 models were slightly shy on peak speed, their rough water stability was so exceptional that riders could still ride wide open while their competitors were getting worn down by their “rougher” rides. Unfortunately, in the pro ranks, the SLTX has certainly had more of a technical struggle. Modified SLTXs are clearly in the hunt for horsepower. However they have yet to permanently resolve a series of driveshaft/driveline problems that turn up when the rpms are significantly increased. We can’t claim to know the full scope of these driveline “gremlins”, however we are developing a Sleeper kit for the SLTX for use in recreational (and endurance) applications. Perhaps the solution will ultimately be increased impeller pitches rather than increased rpms (as is the case on the ’98 SLTXs) As we gather the info, we will post it. Like the Kawasaki, the SLTX only lacks development time…not basic quality.
Sea Doo GTX 785 – There can be no doubt about the unprecedented popularity of this 3-seater machine. Above all, the good ergonomics of the GTX 785 make it a very comfortable machine to ride at speed in rough water. In 1996, it “was” one of the top endurance platforms…even in stock form. However the increasing pace of endurance competition demanded that the GTXs had to be modified. Once this modification work began, the GTXs primary technical weakness began to clearly show.
The GTX utilizes the very successful (and durable) driveline package that was designed for the 95/96XP. In the lightweight XP hull, the acceleration and hook up of this driveline were everything that anybody could want. However, with very few changes, this same driveline was fitted into the 23-inch longer, 140 pound heavier GTX hull. The performance of the GTX is still admirable, but the ability to hook up the pump (under hard acceleration) became a point of increasing difficulty. When the horsepower was significantly increased, this difficulty was also increased. The easy way to solve the hook up problem was to install a Swirl type impeller or a more aggressive scoop grate. These parts could reduce the cavitation, but they also reduced much of the speed that had been gained from the power increase. During our own testing, we netted the best combination of hook up and peak speed using a Solas Xo impeller along with our conventional Sleeper kit. We had other setups that made significantly better power…but never significantly better speeds.
While many racers fought this same technical “catch 22” with mixed results, none came up with a GTX that had the hook up and speed to run with the top triples. The obvious solution for this problem was that this big boat needed a big pump. Even if installing a bigger pump was permitted by the IJSBA rules (which it is not), a bigger pump would induce a load so great that a bigger motor would be needed to pull it. This line of reasoning is, no doubt, what brought about the GTX 950.
Some “Still Fast Enough to be Fun” Recreational Options – Lots of folks are looking for older machines (that can be bought for little money) that have the potential to be reliable, fun, and fast recreational machines. There are plenty of them. As mentioned above, whenever you purchase a used machine, we recommend the lowest hours unit you can find. Basket cases and fixer-uppers are a good bargain only if the price is dirt cheap, and you have the mechanical guile to do the rebuild yourself.
Yamaha 701 Wave Raider – All the first year 701 Raiders sported a hand-laid fiberglass hull. Virtually all these machines had the “purple” bottoms (there are supposed to have been a few white ones, but we never saw one). These “purple bottom” hulls are significantly lighter, and faster, than the white bottom SMC Raiders that followed. If you have a clean purple bottom 701 Raider…keep it. Like the 1100 Raiders, these boats were a bit “evil handling” in rough water. However, also like the 1100s, they generate very impressive peak water speeds on smooth water. A purple bottom 701, with a Sleeper kit and a pipe, will accelerate with virtually anything, and run 59-61 mph. On top of this, they hold 13 gallons of fuel, and are better on gas consumption than any other pwc that can run 60 mph. All this, together with very comfortable 2 person seating, makes this boat a great smooth-water recreation boat/grudge racer…at an affordable price.
Kawasaki 750 Xi/SS/XiR ‘92-’94 – These machines were never the ultimate for high-speed rough water riding, but they certainly offer an excellent mix of great handling, speed, and reliability. Either machine, fitted with a Sleeper kit, could run over 50 mph. The addition of a Coffman pipe added a couple more mph. While the low 50 mph range is not equal to today’s cutting edge machines, these speeds (on a hull this short) make for full time fun. We never found the performance difference between the single carb version (SS), and the dual carb version (Xi) to be that great, but carb tuning on the single carb versions was “lots” easier. The only serious down side of these boats was the incredibly “wet” ride. Blinding walls of water commonly come off the hull into the rider’s face. This problem is easily solved (nowadays) by the installation of a readily available splash-guard.
Kawasaki 650 SX – This stand up boat was made from ’87-’92 with virtually no changes other than graphics. As soon as the 750SX was released, the 650 was considered a machine that was “no longer in vogue”. Vogue or not, today the 650SX is still one of the best high performance stand up bargains around. Casually modified 650SXs are every bit as fast and fun as most 750s. A Sleeper equipped 650SX accelerates strong and runs 45 mph. Most aftermarket pipes will add 2-3 mph to that. Furthermore the great handling of these boats don’t give anything away to their big brother.
These modified 650s have repeatedly proven that they can be more reliable than comparable 750s. The crank of the 650 is every bit as beefy as the 750’s, and the 650’s “closer to square” bore/stroke ratio allows for much longer piston and ring life than the 750 offers. (we would tend to recommend against big bore kits on these machines). Since this stand up is the lightest of all the 650 Kawasaki’s, the relatively light loads allow the SX model engines to last much longer (than they do in the 2-seaters). The other 650 models are nice recreational cruisers, but none of them have the same competitive par with current machines…like the 650SX (still) does.
650cc Yamaha Anything – Of all the older model machines that have good recreational potential, none have better prospects than the 650 (actually 633cc) models from Yamaha. The 633cc motors were among the most reliable and heavy duty pwc engines ever built. However more importantly, these 633s when modified to run with the newer models, do not loose one bit of their excellent long term reliability. We commonly have customers with 633 Sleeper kits (and 685cc big bore Sleeper kits) that run their boats for two or three years with no top end maintenance. The crankshafts in the 633s are the same part used in the 701cc and 753cc models, and offers excellent longevity. Note that since all the 633 models came stock with an aluminum impeller, switching to a stainless prop is considered mandatory.
Perhaps the only 633 models that had any significant weaknesses were the LX model and the Wave Runner 3 models. The LX was the only 633 model that was equipped with the small mixed-flow pump from the earlier 500cc models. Installing a stainless prop into this pump makes a world of difference, but the rough water hook up of this pump (even with a s/s prop) has serious limitations that out-rule this machine for aggressive rough water use…but it’s great on smoother water.
The early 633 Wave Runner 3 models had a somewhat long and frail sub-shaft between the engine coupler and the rear bulkhead wall of the engine compartment. Under heavy use, this shaft would begin to bow and then bend away from the rear engine coupler (it is not a small event when this happens). Most machines were re-fitted with the heavier updated shaft used in the 701cc Wave Runner 3. If you’re planning to buy a used one, you should check for this. For specific info on the speeds of different 633cc models, please see our document “Yamaha 633 and 701”.