I've got a 2001 400EX and I've been noticing a vibration sound recently which seems to be coming from the front of the quad. It sounds like the heat sheild is rattling on the exhaust or something like that, but I've check my exhaust for cracks and I've made sure that all of my nuts and bolts are tight. When riding, I can only here at when riding at high RPM. If I park and hold my head near the engine area while I rev it up, it almost sounds like its coming from the engine. Any idea as to what might be causing it? Valves maybe? I haven't done any mods other than an E-Series. Any input would be appreciated.

Thanks.

 

I have the same exact problem on my Rancher. Right before i hit the rev limiter it starts rattilin. I checked the header cover and it seems to be tight. Anybody know a way to fix it?

 

good question I know what you are talking about any body know anything about it? I just adjusted my valves but I don't think that was what that was.