My honda 400ex is making a loud humming noise in at top of 2nd gear, when I shift into third gear the noise goes away. I looked for any signs of tire rubbing or loose plastic or parts, and theres nothing obstructing. I bought this bike used it has the 440 kit with aftermarket cam and a supertrapp exhaust. The bike runs great superfast and doesnt have any problems other than what I described. Is it possible that I am reaching the rev limit? Prior to this quad I have only owned a honda 250r which does not have a rev limiter. Any advise would be greatly appreciated.

 

id say your reaching the rev limiter if its going away when you shift to the next try not reving it out befor shifting into 3rd bedided that just ride and have a blast on it