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Ok, i obviously have a pretty big problem and have no idea really where to start. I went out riding one day and the raptor started popping and backfiring and would go dead if u didnt stay in the throttle. that would last about 5 min. then it would run fine for about 5 min. it did that for about 30 min. i finally made it back home and noticed that the hose that runs from the throttle body to the intake had vibrated loose. so i put the hose back on and rode it for a few minutes and it ran fine. got back on it the next day and it wouldnt start. changed the plug and it started up but still popping and backfiring. it's now been at the shop for a month and they no idea what's wrong with it. still sounds like a pulpwood truck when it runs. still popping, still backfiring and fouling a plug just about everytime it's cranked. we did put a fuel pressure guage on it and the fuel pressure was good. has anybody heard of this problem before?


06' Raptor 700r SE
white brothers xcr pipe
no fuel programmer yet (could this be a prob.? after running the pipe for 2 months?)

 

have they checked the timing? the engine compression? the spark? is there water in the fuel? is there a vacuum leak? is there a crack in the cylinder head? if all that checks out ok, then its time to look into the electronics end of the bike.

 

Sounds like a lean backfire to me. Check for vaccum leaks between the throttle body and the head. A small tear in a boot or a piece of gasket missing is all it takes to get enough extra air inside to cause a major lean problem.