Hot Dam*it

[fat guy]

ooooooooooooookay, 2002 400ex, hasnt had anything done maintenance wise (internally) since it was brand new. only mods are exhaust and jetting. recently, it started making an offensive vibrating noise in the engine. it sounds like its coming from the top front part, just above the exhaust ports. im thinking maybe its time for a valve adjustment--is that a likely cause of excessive vibration?? it only vibrates like that at about 1/2-WOT rpm range. anyone else had a problem like this? ANY feed back would help, thanks fellas.

Matt

[Ryan]

If you hear any type of ticking or tapping in the top end, chances are you need to ajust your valves.

[300exazzkikr]

It seems like it's time for a valve adjustment anyway, but i don't think that the valves would cause it to vibrate, I would adjust the valves and see if it goes away. Hey it could even be a loose bolt.:huh

a vibration coming from the topend.....adjust your valves and if that doesnt sop it..go buy a manual and start tearing your top end apart until you find sometihng not right

[Mr_Bub400ex]

when its cold out mine vibrates hard on the top end for some reaon

[RED121572]

Sometimes, this will cause a vibration. lol

Seriously though, Ive had three pistons in mine. Ive always had the vib at midrange.

Originally posted by RED121572
Sometimes, this will cause a vibration. lol

Seriously though, Ive had three pistons in mine. Ive always had the vib at midrange.

yea that would cause a few problems with vibrations....also cuase your smoke to be blue..ive had it happen to...it sucks to crack a piston and gouge cylinder liek that....although mine wasnt as bad as yours...mine was still bad enough

[big-guy]

make sure the fenders are bolted on tight, especially right above the front shock mounts.

[240GNCC400]

what octane gas are you running
mine did the same thing, i put an octane booster in the gas for the last race and it didnt do it, could be coincidence though, havent ridden it enough to know if that solved it for good