I have a warrior e series exhaust and kn filter what main jet should i use.[img]i/expressions/face-icon-small-confused.gif[/img]

 

I called White Brothers yesterday about mine. It's a 250ex using a w/b E-series Uni-filter and they said just go up one size from stock. I've been doing a lot of searching around and most seem to go up 2 and sometimes 3. You should try putting vents in your air box. More in More out!

 

I just put a FMF system on my 97 and I bumped the main jet to a 152.5. I ran it for the first time last night and I didnt have much if any backfiring, so I think that is about right. FMF has a great jetting tool on their website. www.fmfracing.com check it out I think it will help

Aaron