57 mm bore and a 51 mm stroke crankshaft will yield you 130cc. Therefore, valve timings are: Transfer ports 130°, exhaust port 190°, blow-down 30°. Commonly, NKG B9ES or Bosch W3CC spark plugs are used. The SP09 is supplied with fuel through the intake in the crankcase. What seperates the SP09 and SP09 Ovale are their exhaust port designs. Whereas the SP09 has a bridged exhaust port, creating two separate exhaust windows, also referred to as a “butterfly port”, the SP09 oval has a “normal” oval port.
The mastermind behind the “Hammerzombie” managed to get 23 hp at the rear wheel with the SP09 on his Polini rotary valve engine. Obviously, this kit already bears a lot of potential in its stock state. However, the working of the exhaust port’s bridge should be checked, just to be safe. Provided with the kit is a massive CNC cylinder head with a symmetrical combustion chamber.
- Easily achieved 20 hp with a lot of potential
- Parmakit’s carburettor recommendation: 26-36 mm
- We recommend bgm PWKs with 24-30 mm, as well as Keihin PWMs and Mikunis
- The exhaust flange’s diameter amounts to 36 mm, space between flange studs is 62 mm
Conclusion: The sky’s the limit, baby!