I've got an 01' raptor with only a slip on gytr pipe, starts, idles, and run fine when just putting around... HOWEVER, when you start to get the rpm's up in 2nd.. 3rd... gear and so forth it spits and sputters like its starving for fuel, sometimes even backfires and dies.. but if you let off the gas and run through the gears at low rpm's everything runs fine with no problems. Only backfires, spits, sputters, etc... when you really start to throttle. Any ideas???? fuel? jetting? filter? electric? etc????? THANK YOU!

 

Try moving your needles .

 

What size jets are in it now?? It sounds like the thing is running way lean in the mid to upper throttle levels. Most likely a main jet change will be in order. I'm close to you so I can probably get you in the ball park just off the top of my head. Just let me know what kinda air filter and stuff you're running on that end.

 

BlackWidow, sent you a pm.