I have 2001 Honda xr400. Predominantly my riding consists of single trails in the North West of Washington state. What I am trying to accomplish is to give the engine second life, without sacrificing its reliability and spending too much $$.

Considering that this is an air cooled bike with 9.3:1 compression ratio I did not want to choose a kit that would increase the compression to the levels where I had to start using race gas. The same goes for a clutch. If you increase the power too much the clutch will start to go faster as well. Keep it simple.

I am going to bore the cylinder from 85 mm to 87 mm which will increase displacement from 397 cmm to 416 cmm and install piston with 10:1 compression ratio. The kit goes for about $150.00 plus $80.00 for boring and honing of a cylinder. 3 years ago