I have a 2002 Honda TRX 400EX when I am giving it full throttle whether in neutral or in a gear the rev of the motor fluctuates. I have completely cleaned out every jet of the carburetor and cleaned the carburetor itself. Sorry if I'm not describing it well. But when you're at the top of a revV it's usually a constant sound and mine sounds like it's happening in a wave pattern. This only happens at full throttle. Any other throttle position and it acts normal. Is there anyone that can tell me what is going on?

 

Don't know the EX, but CDIs have rev limiters built into them to stop you over-revving the engine, it may simply be hitting the limiter. Another possibility, the fuel pipe not able to supply enough fuel when on max revs due to a blocked tank filter, check the fuel flow into the carb.

 

I have owned it for three years now. This is the second time within the past 6 months it is done it. I have pushed this hard and never hit a limiter before. So I will check the fuel. Thank you.