Motorcycle Repair: 82 XL500r tapping, valve lifter, compression stroke

Question
Hello there,

I have an '82 xl500r (honda) and in what sounds to be in the top end i have a constant loud tapping. The bike runs like a champ and is in near showroom condition, so no plans to part with. Though I am concerned with the tapping. I just recently received the bike in a trade from the original owner. It has on 5k miles on the engine but I think it does have quite a bit of hours. Do you have any ideas where I should begin looking? I'm  thinking, timing chain, or something along those lines please respond.  

Answer
Chris, Hmmmm I haven't laid a wrench on one of those for about 20 years, but loud tapping isn't a usual sound for one of those bikes. First, check the valve clearances! .002" for intakes and .004" for the exhausts, checked COLD on the compression stroke. If the clearances are okay, then go to the camchain tensioner. If you leave the valve cover off and get a wrench on the crankshaft, you can turn the crankshaft back and forth, watching the valves to see if they are following the crankshaft movement exactly (check when a valve is partially opened). If there is a "pause" feeling as you turn the motor forward and backwards, then the camchain needs tensioning.

http://www.powersportspro.com/partsfish/login.asp

Go there and find your model. It looks like there are two different styles of tensioners used. Both are attached at the top and the lower attachment, if a nut/washer will release the camchain tensioner adjustment. The other type may be fully automatic, but you can loosen the lower bolt, anyway, just to check (1/2-1 turn). Check tension at TDC compression stroke, like when you did the valves.

The other thing that can make noise is if the decompression release arm (valve lifter) cable is out of adjustment and engaging the valves lightly. You can probably feel any vibration by putting your fingers on the cable arm when the engine is running. If it is vibrating and making the noise, you need to put more slack in the cable, so it will fully release.

Hopefully, your cam and cam followers aren't damaged from some kind of lack of lubrication, at some point in time.

Bill Silver