I sold my 2001 Raptor to my neighbor a few weeks ago. I had installed a Big Gun Quiet series pipe and rejetted to 150/155 with the airbox lid on. It always ran perfect for me. He now has a problem. It idles normally but as soon as the throttle is applied, it makes a loud popping noise. He replaced the coil and it didn't help. Does anyone have suggestions?

 

The Rev limiter swich for the parking brake might be sticking.

 

The motor is lean, so check for intake leaks ,low float, low level in tank.
If thats ok, try going richer on the mixture screw, 1/2 turn should straighten it out.

 

Thanks for the replies, I'll pass them along. When and if he cures the problem, I'll post what it was.

 

six six T, you were exactly right. My neighbor disconnected the parking brake switch and now he's back on the trail. Thanks very much.