Finally the length of the piston. You dont want it hitting the crank at the bottom of the stroke. The actual diameter of the piston in the rs barrel matters not a lot. I think its ok. I recall a few 100's becoming 125's on the quiet. The rs came as a 125and a 100cc.
. f495gbbupe.pages.dev/188f495gbbupe.pages.dev/260f495gbbupe.pages.dev/319f495gbbupe.pages.dev/216f495gbbupe.pages.dev/21f495gbbupe.pages.dev/156f495gbbupe.pages.dev/157f495gbbupe.pages.dev/171f495gbbupe.pages.dev/377
yamaha rs 100 modified