it doesn't go away when i pull clutch lever
can i do anything about it when it's the primary chain?
is it possible cam chain makes heavy noise at idle speed and no noise when you rev up?
Primary chains can only be accessed with complete engine teardown. The primary chain tensioner can be accessed by removing the lower crankcase, something short of a teardown, but engine must come out of frame. How many miles on it?
The tensioner has been shown here to be a weak link. They don't fail, they just become weak. I am replacing mine in my project with a new one, which is obviously stronger than one with 50,000 miles on it and i am placing a preload chip under the spring, an idea of Rob at voxonda.
Not so likely the cam chain will quiet down with revs other than other noise will overtake it. Still it needs a proper tensioning. If you cam chain tensioner is stuck, it may be that the adjustment has been attempted but it didn't take. This is a common problem with high mileage and/or neglected CB750s. The tensioner plunger gets stuck. When you loosen the lock bolt it is supposed to jump forward under spring pressure and take the slack out of the chain. Then you retighten the lock bolt to hold it there. But if the plunger was stuck, loosening and tightening the bolt accomplishes nothing.
All of this should be done with the engine at 15 degrees after top dead center (ATDC) on cyl 1-3 per manual.
