After running my 05 raptor 350 for about 10-15 minutes and it is warmed up, it does not want to idle and it dies, and then sometimes it is hard to start. It acts like it is getting more air than fuel. I think the fuel/air mixture is wrong but can not find the a fuel/air mixture screw to adjust. It tries to die while at idle and it will pop, sputter, and backfire while riding. The backfire seems like a timing issue to me. Also while at idle, if I adjust the idle screw to keep it from dying, the rpms are too high. All of this happens after the quad is warmed up. It runs just fine until after the warm up. Any suggestions???
Just a hunch, had this happen to a bike of mine years ago, could be the piston rings are gettting ready to go(wore down). What happens is when the quad is cold the rings expand tight into the cylinder walls allowing it to get full compression and run ok. When it heats up they shrink allowing the slightest amount of give which in turn will cause you problems similar to what your describing.
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