TOPIC:

I've noticed lately when the motor on my 86 gets hot there's an intermittent tapping noise. Only happens when motor is hot - as in driving in stop and go traffic, and only at idle. If you listen to the attached audio file ("tapping.zip" - it's a .m4a that's been Zip'ed), you can hear the light tapping 'under' the other motor sounds (at about 17 seconds the background motor sound changes as I moved my phone closer to the motor). Is that tapping sound familiar to anyone?

Edit: I used some noise reduction techniques on the original audio file to highlight the tapping sound and have re-attached the file.

Sure sounds like a loose timing chain. I hear a bright tinking sound like a chain bouncing off of an aluminum casting. What do you have for a cam chain tensioner? The Stock one or a modified one or a manual adjust one? Note that at idle, the action of the camshaft on the cam followers causes the timing chain to feel a lot of pull push from the cams and if the chain is loose, there will be a lot of jerking in the chain. As you speed up those jerking movements sort of roll together which would reduce the noise.
I hear a lot of throaty air noise. Is the airbox off during the taking of the sound track?

Hi Kawboy. Thanks for your note. Cam chain tensioner is original with the factory oil line hooked up to it. Original air box and filter installed, not sure what your hearing when you mention 'air noise' - could be an artifact of the noise reduction.

Something I just discovered after a long ride today. If I pull up to a stop with the bike in gear and the clutch pulled in, the 'tapping' noise is not there, but when I go into neutral and release the clutch, the tapping begins immediately. Can reproduce by putting it back in gear and letting out the clutch slightly - noise disappears, only to reappear when back in neutral.

So depending on the mileage, the secondary chain could be worn enough to bounce off of a web in the lower crankcase and that would happen at idle with no load. Simulate the noise again and with the bike on the center stand, get down and listen to the bottom of the engine.
I can't remember who discovered this before, but it was posted showing the chewed web in the lower case. For whatever reason D Carver ( member) seems to ring a bell.

Mileage is pretty low - less than 8k.

It seems like the weather is going to hold for a few days so I'm hoping to get out for a few more rides before the insurance lapses for the winter. Good idea about getting underneath - I'll get my mechanics stethoscope out.

Does the noise go away if you pull in the clutch?