my raptor has been jetted repeatedly, but only the main jet, and air/fuel adjusment screw. when ever i let off the gas and let the ngine slow me, it back fires repeatedly, the person behind me even told me he saw huge flames shooting out the muffler. what should i check, btw, for all my mods, i have 145/150 main jet, 1/4 inches holes in the lid and no snorkel.

 

sounds like your running lean mine does that to '' warrior''

 

Back out your air screws a little and go up on the mains. That's my opinion. How does your plug look?

 

Its caused by a lean condition in the idle circuit. Check for air leaks in the intake and exhaust. If they are good, go richer on the mixture screw, and if you get to more than 4 turns out from seated...you need a bigger pilot jet.

 

Like hondabuster said, check for air leaks,,,especially cracked or torn intake boots. I have an 01 raptor with a full fmf exhaust,,and it just would not run right till i installed a dynojet stage 2 kit. I must have taken the carbs apart 20 times, trying all kinds of different jetting combos. Trial and error sucks on these things. Get yourself a dynojet stage 2 kit, and follow the instructions according to your elevation,,,,,you will be happy.