Zcar,
I have a KZ1100D1 '82 with suffers from what appears to be the same problem; a symmetric 'valve noise' from the engine case in the clutch area. Noise when idling in neutral, noise when revving in neutral, noise when idling in gear with clutch disengaged, but no noise when engaging clutch in gear (a.k.a. riding). I don't think this is the hy-vo (nor the cam chain) since the noise doesn't go away when revving in neutral. Also, a worn bearing would create noise under load, not the other way around, wouldn't it?
Zcar, did you identify the cause of your problem? Anyone else out there who has a clue?
