I have a 440ex and today when I hit high rpm it started cutting back on me. I changed the spark plug but wasn't the problem . I have a White Brothers exhaust and dyno jet kit with it. It runs okay at idle speed. I don't want to take it to shop . Any advice would really help . Thanks

 

check your your choke mine is bad to fip on when i hit a jump and land hard

 

I just found the problem out awhile ago when I decided to take my carb. off . The breather clamp that connects to the carburator came off while I was at a mx track .I guess all the jumping knocked it off.