04 Raptor 350.New GYT-R midpipe/slipon/high-flo filter/outer wear.Here goes,pilot stock,main 160,needle 3rd.air screw 3 turns out.This was the starting point.Off idle too three quarter throttle good,after that it sounds like a small miss or backfire to wide open throttle.Moved the needle to middle position no change?Took the air box lid off much better.Now,should I move the needle back 3rd,and drop the main jet.Plug is pretty Black which means rich,cleaned up with lid off,greyish white on tip of plug,tan brown on electrode.I need to run with the lid if at all possible,it is very dusty where I usually ride.Any help would good,Im real close it wants too run hard,just this little stumble?Elevation about 1,200 to 1,500 feet.

 

Ok Pilot is low end...Needle is Mid...Main is top (theres a graph somewhere i'll try to find it) Search the forums for Realistic Raptor, the post was made by 2fun and he put really good jetting tips. I suggest you drop a main jet first and try that out

 

That is what I am thinking too, the plug is showing that it is rich.I know someone put up a couple links that were really good on this subject,but I can not find them now.I did a search on jetting but still could not find them.Thank you for the reply,anyone else?I am so frigging close.