I was just wondering if anyone out there can help me. I have a 2005 Raptor 350 that I inherited from a friend who defaulted on his loan that I co-signed for, this machine would definitely not be my first choice but it's definitely much better in the tight trails than my 450r. Anyway it seems to backfire through the carb mostly at lower RPMs but sometimes at the higher RPMs too. The quad is completely stock and doesn't even have that many hours on it but it's been rode pretty hard. I've checked the timing, valve clearance, and went through the carb but everything seemed good. Maybe I missed something, I do know how to work on them I'm just not all that great at diagnosing the problems because there's still some things I don't know. Any suggestions?

 

see if its the parking brake sensor the wire that runs off your clutch perch, unplug it then recconect the two wires you unplug and put them together that way there not actually connected to the parking brake, also id check your wiring and grounds, id guess if its got really crappy fuel in it then that might cause something, id check your spark plug too and see what it looks like

 

Does it run good enough to ride it? Or does it backfire when you are just sitting there playing with the throttle? Usually a major backfire through the carb will shut the bike off and sometimes start a small fire. If that happens you have major engine problems or your timings off, but you already checked that. Other times a small backfire is what I call a "hiccup", where the engine keeps running, but just stumbles and stutters. If it is hiccup problems you are having, it could be caused by a rich carb, or not getting enough air. Check the air filter to make sure it is clean and check the air screw to make sure it is properly adjusted. Or it could be jetted too rich from the factory for your climate and elevation. If your weather has been 95-100 degrees lately and you live in a lower elevation, you may need to replace the main jet with 1 size smaller.