[storm720]

I need some recommendations for sprocket selection for a 2007 CRF150F. It has Pipe, jetting, air box mod. I've read the 420 set up is prime, but what about tooth count in the rear compared to stock? Thanks.

[crfsonly]

use are gearing/rpm/speed calculator found here:

http://crfsonly.com/howto/gearing/motor ... ulator.php

it will help you determine what is the best final drive gearing for your needs.

ken