Motorcycle Repair: Yamaha XJ 750, yamaha xj 750, crankshaft bearings

Question
Hi Chris, my name is Bernard and i am from South Africa.I ride a yamaha xj 750 and urgently need some advice regarding the clutch.The motorcycle runs fine, but, the minute i exceed 100km/ph there is a really bad vibration from the engine,i suspect it is the clutch because it also occurs if i rev the engine hard when the bike is freestanding in neutral.The clutch lever is very stiff and i have tried lubing the cable which seems to work for a short while, however, the vibration remains.I have had the rear wheel balanced as part of a process of ilimination, i have also checked the plates and clutch basket, however, i am no authority.The motor runs beautifully through this all.Please advise.Thanks Bernard. bpollet@yahoo.com  

Answer
Hi Bernard.

The fact that you have this vibration even when the bike is in neutral is indicative of a problem with something other than the clutch.

Were it the clutch, the vibration would occur only when the clutch is engaged.

You could be looking at an issue with the crankshaft, crankshaft bearings or pistons.

You may want to have that looked at.

Good luck and ride safe.
FALCON