Ok heres the thing, my 2001 400ex is sputtering at 3/4 to full throttle. It has great throttle response up until that point. I'm running a k&n jet kit iwth filter and no air box lid. Also a WB e-series slip on with 12 discs. I was originally running a 165 main and thought maybe it was a little rich so i switched to a 160 but still sputters at high rpm's. What could be causing this? Any suggestions would be awesome. Thanks in advance!!!
Matt