Bought a 02 stock raptor in October and love it. It ran fine but starting in December it started to act up. It idles fine but when i give it gas it sputters and back fires. Only did this occasionally but now does it all the time. The carbs did not blow off, and Im thinking its the jetting or mixture. But I dont want to fool with the carb if thats not the problem. Does anyone know what this sounds like. Thanks

 

Things I would check:
Stuck choke
Rev limiters for the parking brake and reverse, most likely the problem.
Float level, very easy to check. Do a search on how to do it.

 

When the proplem started everything was stock. no jet kit nothing. I just put on a GYT-R slip on and a high flow airfilter with no lid. Problem has gotten worse. A GTY-R jet kit is on the way hoping that will solve the problem. Havent been able to ride it since January due to this problem. Thanks for your info.

 

With those mods turn out your mixture screws, 3 turns out will be close.Also adjust your valves if you have'nt yet. The intakes tend to tighten up and could cause the same type of problems.

 

You need to rejet whenever you play with the amount of air flowing in and out of the quad, you are running lean i bet. Get the jet kit in there, put the jets they suggest for your mod//elevation. Since it got colder you will run leaner as well, the air is more dense therefore you get more into the engine. Shouldn't effect it too much, rejet and tell us how it goes.