I have taken out the air restricion and the spark arrestor on my raptor. In warmer weather it backfires, but not in colder weather. Does anyone have any ideas on what to do? I have a race this sunday, I need some help.

Thanks

 

Raise the needle one position and go up one size on the pilot. That's what one of the pipe manufacturers said. On mine I have also gone up a size on the main, but I'm at sealevel.

 

Do you know the specific type of main jet, or did you just remove them and match it up with another one? You are running a 145 and 150 now?

 

what is the stock jetting?

 

for what you have done to your raptor the main jet size should be ok but it wouldnt hurt to go up one size. that would be a 142.5 left side carb and a 147.5 on the right side.stock is 140,145.if you change you main jet the needle will be ok and should either adjust your idle mixture screw or go up one size on the pilot jet.