I just purchased a 2004 raptor 350. It has a wiseco crank and piston(10.25 to 1- up from stock 9.2 to 1), a 07 yoshimura trc comp series full exhaust, and pro design kit with k&n filter. Not sure about cam but I believe its stock. Its been sitting for awhile so I took off the carb and cleaned it and noticed that it had the stock jetts still in it-142.5 main and 22.5 pilot and 2 1/4 turns out. I'm new to atv's but comon sense tell's me to rejet. My question is if I need to rejet, what would be a good place to start with my setup? Also, I've heard about over heating problems when increasing compression. Do I need to add a oil cooler or fan? Thanks for any help.

 

You don't have to add an oil cooler. I had 2 Warriors with a 10.5:1 JE piston with no oil cooler and never had any problems - at the drag strip or on tight trails. I think a 150 main jet would be a good start. You can probably get away with the stock pilot and raise your needle 1-2 notches.

 

Thanks Rap,
That's what I needed to know.