Ok i have a pretty modified Yamaha Blaster, 97. I have Pro Circuit exhaust, K+n air filter, reed spacer, carbon fiber reeds, and a vitos superstock piston kit. I don't know what size jets to run, and i don't know how to adjust them. I know i should rejet it all, cause i neve hav before, never known what to do. Help me out, please.[img]i/expressions/face-icon-small-confused.gif[/img]

 

You are letting in more air into the motor, AND allowing more air out, therefore you will need to go UP on the main jet, and possibly the pilot. You may also need to drop the clip on the needle a position or two.

If you do not already have one, get a manual. They are INVALUABLE, and can be purchased for under 25 bucks (way less than you have in mods already).

For comparison, my blaster has an FMF "Fatty" pipe, and a K&N airfilter with an outerware.
I am currently running a 290-300 main jet (230 is stock).

I would say start out with a 300 main, and do a plug check.

You may also want to drop the clip on the needle 1 or 2 positions (raising the needle) in order to richen up the midrange also.[img]i/expressions/face-icon-small-wink.gif[/img]