Geez, you guys lost me a long time ago. One question, how do you figure out what the "stroke" is? Looks like you need it to calculate the new cc's. Maybe I'll understand some day. Later.

-Josh

 

Stroke doesn't change with a bigger piston, so just use the stock stroke figure. All the stock bore and stroke figures are publsihed at www.yamahausa.com

Brad

 

.020" is 2/100ths of an inch it probly is .5mm I'm not sure. Any way its not much just enough to put a fresh surface in the cylinder bore. It is hard and expensive to make a warrior as fast as a 400ex it would require a big bore or stroker kit to run side by side with a 400ex. I would buy a new pipe, cam, and have the head ported. They are reasonably cheap compaired to an engine kit. You could gear your warrior to go as fast as a 400ex but the 400 would be way ahead of you by the time you got wound out.