Kawasaki Ultra – STXR Carb Manifolds – Single Pipe Boats

When the Kawasaki Ultra was first released in 1999, R&D manufactured this short billet manifold for owners who wished to install 44/46/48 Mikuni carbs…. And they worked great.

When the FPP triple pipes were developed, the carbs had to rotated at a different angle, and held slightly farther away from the engine to allow for pipe routing. This increased inlet length and angle significantly increased the interior volume of the new manifolds (with or without the “M-16” reed cages). Since the triple pipes themselves induce a huge increase in inlet signal, the extra volume of this new manifold was of no consequence on triple pipe machines. With that, R&D discontinued the old “short” billet” manifold.

Sadly, the extra volume in these new “triple pipe” inlet manifolds has a very serious negative effect when applied to a machine that uses the stock single pipe. The extra volume of the “triple pipe” manifolds seriously weakens the inlet signal on a single pipe setup to the extent where there are huge losses in acceleration and peak rpm. We tested at length on a single pipe STXR, with the new “longer” manifolds, to try to resolve these performance problems through tuning … with no success. By simply removing the new “long” manifolds, and installing the early style “short” manifolds, our single pipe machine gained a huge margin of acceleration, and peak rpm.

As a result, Group K now offers this early style manifold for owners who want the full benefit of Mikuni carbs on their single pipe Ultras & STXRs. We used the manifolds in conjunction with a special R&D reed stuffer to perfectly mate up to the stock reed cages. This short-manifold/reed stuffer combination gives excellent inlet signal, yet still accommodates the volume needs of the popular 48mm Novi carbs.

For owners that want the absolute maximum power from their single pipe Kawasaki 1200, these manifolds are unmatched. We typically used them with the reed stuffers and the stock reed cages (and stock petals).

These manifolds will accommodate carbs that mount by the 2 bolt flanges, or the rubber spigots. We tend to prefer the bolt-on flange setup. Even though the initial installation is a bit more difficult, it has less inlet tract length than the setup that employs the use of the rubber spigots (a shorter inlet tract is much better on the single pipe setups.

All the 48 Novi conversions that we installed used carbs with no built in fuel pumps. This allowed us to feed all three carbs with a single remote Mikuni DF-62 pump. This pump feeds more fuel than any machine will ever need, and avoids the need to drill additional pulse line fittings into the crankcase. In addition, having the remote pump gives owners the option to include a fuel/air separator canister.