TOPIC:

My 79 A1 has developed 'clunky' sound at idle. 

Anything above idle and all is smooth. By idle, I mean around 1k rpm or less. 
Bike has APE manual cam chain tensioner, which I'll look at, but this sounds deeper in frequency than what I imagine cam chain 'slap' to be...

Noticed last shutdown that the noise was noticeably worse when crankshaft slowing down with no ignition... 
and the noise seems to be coming from the LHS alternator/starter cover. This A1 has the rare 79 LHS alternator conversion, OEM.

I've been reluctant to adjust the APE, probably a petty unfounded fear of jumping a tooth or something when loosening to hear 'slack' prior to tightening back up. And as stated earlier, clunk clunk not slap slap..

Need to check valve clearance anyway, so will look at cam chain tension when cover is off.. .to get a baseline.
...and, will pull LHS alt/starter clutch cover to have a peek there too.

T-2 hours to spinning wrenches...
Wish me luck, I need it.
 

There are 3 allen head cap screws item #1 that hold the starter clutch item #6 to the torsion damper iitem #28 that have a tendency to come loose and have done some significant damage in the past. If the sound is coming from the left cover, that's likely what's happening here.
KB

 

dcarver220b wrote:

My 79 A1 has developed 'clunky' sound at idle. 

I've been reluctant to adjust the APE, probably a petty unfounded fear of jumping a tooth or something when loosening to hear 'slack' prior to tightening back up. And as stated earlier, clunk clunk not slap slap..

Need to check valve clearance anyway, so will look at cam chain tension when cover is off.. .to get a baseline.
...and, will pull LHS alt/starter clutch cover to have a peek there too.

T-2 hours to spinning wrenches...
Wish me luck, I need it.

 

Regarding the APE tensioner, as far as adjusting goes- back off the locknut and rotate the adjuster bolt in with your fingers until tension is felt, then in another 1/6 of a turn and lock it up. Do this while the engine is running. if you were to do this when the engine is stopped, depending on exactly where the cam chain was stopped, the lobes on the camshaft will tend to pull the cam chain tight or loose and will give you a false feel. When you do the adjustment when running at idle, you'll feel the adjuster bolt  pulsing slightly and then as you tighten it in, the feeling will smooth out as the slack is taken up. At that point add another 1/6 of a turn in and lock it up.

Kawboy wrote:

There are 3 allen head cap screws item #1 that hold the starter clutch item #6 to the torsion damper iitem #28 that have a tendency to come loose and have done some significant damage in the past. If the sound is coming from the left cover, that's likely what's happening here.
KB

 

Thanks KB, it's been years since I've been inside.. as Ray, RIP, performed engine rebuild. Believe it or not, I have a spare unit under wraps. But sure would hate to have loose parts causing gear burger..
 

"Regarding the APE tensioner, as far as adjusting goes- back off the locknut and rotate the adjuster bolt in with your fingers until tension is felt, then in another 1/6 of a turn and lock it up. Do this while the engine is running. if you were to do this when the engine is stopped, depending on exactly where the cam chain was stopped, the lobes on the camshaft will tend to pull the cam chain tight or loose and will give you a false feel. When you do the adjustment when running at idle, you'll feel the adjuster bolt  pulsing slightly and then as you tighten it in, the feeling will smooth out as the slack is taken up. At that point add another 1/6 of a turn in and lock it up."

Thanks for the excellent procedure, you could have a career in nuclear power! 

Removed valve cover and put eyeball and screwdriver on cam chain.
If anything, I think it might be too tight?

Ok, got to give it up. Awhile back I was messing with it, lost my 'index' mark and added another 1/8 or 1/4 turn and buttoned it up.
Mia Culpa.

Here's a video.. which I realize is not worth much, and I will perform the procedure you described above.

Ok, got after the KZ clunky sounds syndrome today...

For full text and pics, <clicky>