Topic: CB650 is new machine to me and I have a question about engine/drivetrain noise.

[Duck]

The CB650 runs well but there is a knocking noise at low RPM.
Listening with a piece of 1/2 " copper water pipe, it seems loudest in the vicinity of the clutch cover.
It's definitely less noisy when lietening to other parts of the engine. Second loudest is opposite side near end of countershaft.
I don't hear it any more once up to 2000 RPM or so.
It's a little quiter/different with the bike in gear on the centerstand.
Sounds like a dull knocking sound.
I don't have the manual handy. It's 45min ride away at my workshop.

Does the CB650 drive the countershaft with a chain? Sounds almost like a flat-wide piece of metal just barely bumping the case from the inside.

I searched through the forums and tech info and found some reference to clutch rattle. The only clutch rattle I'm familiar with is the very noisy dry clutch on the ducati's.
Definitely doesn't sound like that! I really don't hear anything like a rattle.

Any ideas?

-Duck

[DammitDan]

On my '82 650 the clutch has always knocked like that.  It gets worse when it's cold and/or in neutral.  When it's in gear it almost goes away.

It sounds like what you're talking about is the clutch rattle you've read about.  I've found adjusting the clutch adjuster screw on the cover helps, as well as adjusting the clutch cable.

Also, if you sync your carbs it will help immensely.  Something about the pistons fighting eachother when it's out of sync really enhances the clutch rattle.

[Duck]

I found an online manual.
The CB650 has a cush-damper on a chain driven primary shaft.
-Duck