Exhaust "Click"

My '89, bone stock as far as engine and exhaust, has 20K miles. Owned since new and well maintained, with valve adjustment 3K ago. For some time I've had a loud, hollow, metallic click emanating from the can (muffler) when I roll off the throttle. Assumed it was some sort of loose baffle, but now I'm persuaded there's some different problem, like a minor detonation in the pipe. (valve not seating? carbon? air leak? mixture? carb? pollution plumbing?). Took the tank off and the air filter last night, no effect. Bike starts and runs fine, although it seems just a bit rich. ("Choke" is working fine - not stuck open) Anyone with experience with this "clicking" sound or who can point me in the right direction to start looking?

Also, anyone got a new clutch cable they want to sell?

While I don't think it is the problem, the choke can be stuck open without obvious symptoms. Mine needed replacing at about 15K. I had slightly increased vibration and slightly decreased gas mileage. A mechanic I trust suggested replacing the choke cable because he believed that one of the choke needles was hanging up. i disassembled the original cable at the carbs, found no problem and reassembled it. Everything appeared fine. I finally replaced the cable and the symptoms went away. It's not the cable hanging up, it's the choke needle. BTW, expect sticker shock ($54 as I recall) and a royal PIA replacing the cable if you go that route.

I'm a bit confused. You said it wasn't the cable, but that's what you replaced to fix it? Last night I checked the valve clearances, they were fine. But now that you mention it, my choke lever has been feeling a bit strange lately, so I'll examine that and try to pull the enrichment circuit guts out and clean them. If that works, I'll report back. Thanks for the lead.

Follow the choke cable down to the left carb. There is a plastic nut that links it to the carb. Disconnect it and you will see that it ends in a small cylinder with a needle, i.e., it's not a 'choke' but an enrichening valve. Do the left side because getting at the right is a real bitch while the left one is easy. It is the needle which gets hung up and you need to replace the cable to replace the needles. Again, I couldn't see anything wrong with eiter side, but replacing the cable fixed the problem. And, again, the mechanic who diagnosed the problem is one of the best I have ever met. He knew what it was instantly when I described the problem. That leads me to beleive it is not an unusual problem.