400EX Vibrating Badly! Please Help!!

[ghawkman]

My 2001 400EX just started vibrating very badly and getting much hotter than normal. One shop said without tear down, I need a new top end. I didn't belive them so I tore the top end apart and looked at the cam, valves, piston, rings, etc... I see no damage from sand at all. The connecting rod to the piston is not loose. I do have oil on the side of the motor where the flywheel is. I don't think that is normal is it? If not, then possibly that crank bearing and seal on that side are bad allowing oil into that side of the motor, which would explain the vibration. I want to get all your ideas to look at before I get myself into trouble tearing apart the whole bottom end.

ANy ideas what could cause a very bad vibration at idle and gets worse at high revs? Is there anything in the top end that could cause a motor to vibrate that bad? There was some noise in the very top end that sounded like there was no oil in it. But the oil was full..

Please help!!!!! PLEASE... I am so lost with out my bike. It is near new. Only ridden about 8 times only in the sand!!

did u break it in properly? Is an engine mount(s) broke or missing a bolt? Does it still run fine or it just vibrates a lot.

[ghawkman]

It runs exactly the same. No loss of power. It vibrates so bad my hands and feet almost became numb. Plus it got very, very hot and stayed hot for a couple of hours....

[MIKE400EX]

Check the flywheel and woodruff key. A little oil on that side is normal.

[400grl]

The shop you talked to probably suspects blow-by since you rode it in the sand ......

And...here is a girl question for you all - could something like that be caused by a bad head gasket?

[Juggalo]

one time my LT started vibrating really bad..turns out the counterbalancer sheared off the key and it also knowkc a hole in the case. hope that didn't happen to you..

[300exazzkikr]

I would take the stator side cover off and look in there. sounds to me that something might have cracked. I'm going with the counterbalancer like juggalo said.

[mod300ex]

crank bearing on my kx went once and it vibrated liek what ur sayin and also got really hot