i put a pipe and the correct jets on a 02 400ex this spring and it ran fine now when it getts in the higher rpm range it falls on its face i figured it was just because the weather got warm but when i changed the jet it only made it worse so i adjusted the valves that wasnt it either any help or suggestions would be great

 

which way did you go on the jetting. need more info

 

I would agree with fulltiltrider. we need more info maybe when u jetted and it was fine but then that wether came and lets say for example u started running rich and then u rejet but u jet richer that would just make it worse... u could pssibly try leaning it up some and see if that helps.. just some advice