I have a 04 400ex with a HMF slip on. The pipe recommended i go up 4 each on the main and slow jet. I did this but i didnt do 2.5 turns on the fuel screw like it was suggested. THe pipe now doesnt sound as good it it acts like its out of gas in the top of 5th. But if i take the air lid off it doesnt do this and it runs fine. I was thinkin bout gettin a ehs lid and a uni filter. I need help quick on this so if anybody has anysuggestions any help is aprreciated. Thanks

 

well to me it sounds like it is running rich. when you remove the air box lid that would lean it out. thats what it sounds like to me,have you checked your spark plug?
phil

 

Ya i have cheacked my plug but that was right after i jetted it. It was runnen a little lean but it could be from before i jetted it because i ran it with the pipe on and no jets for like 2 weeks. Thanks for ur reply.