4 stroke performance mods

[scottyo]

I was wondering if anybody could suggest some simple, easy 4 stroke performance mods I could make to my bike once its finished?

Do expansion exhausts apply to 4 stroke engines?

I am eagerly waiting for SBP's 4 stroke jackshaft kit to come out.

 

[motorbikemike45]

Expansion chambers work on 2 strokes, not so well on 4 cycle engines. Carburetor, compression, camshaft lift+duration+timing, valve size, spark strength+timing, and the free flow of gasses from the air cleaner to the exhaust tip are where power and torque can be improved. It doesn't seem to matter much if it's a big V8 or a micro engine, the ways to increase performance in 4 cycle engines are the same. Old Bob made a link to a primer on performance mods on a post I made on modding a Robin in the 4 stroke section. That would be a good read as a starter.