Prospective GS owner here.
I looked at a GS on the weekend, older but in pretty good shape. One thing I did notice was there seemed to be a definite noise from what sounded like the cam chain, not rattly so much as just noisy (sorry, it's hard to describe a noise )
Can anyone tell me whether the cam chain is usually quite noisy on a GS, whether there's a tensioner that maybe gets a bit worn over the years and doesn't tension the chain properly, or maybe if the oil level isn't right, that could promote the motor being mechanically loud, or perhaps even the motor gets loud when the valves need adjusting?.
Any advice would be much appreciated - I do think I'll buy this bike, just a little concerned as to whether it needs something before I ride it too far.
Thanks
Shane

The GS's valves are loud, but that's a very distinct ticking sound.

The GS does have a cam chain adjuster that sits behind the cylinders under the carburetors. You can remove that, turn the tensioner plunger  in and see if it extends all by itselw, as it should. At that time chekc for wear at the end of the plunger. If there is any, that's higly suspicious, ast he chain runs on a ril, which in turn is pressed against the chain with the plunger.

Thanks. It's not the valves, it's not that 'ticking' sound you get with clearance issues. Does the tensioner lose tension over time? I presume it's an automatic type, doesn't need adjusting, right?
Thanks

Yep, automatic type. It's a spring loaded unit with a ratchet mechanism (or equivalent, don't know how it works exaclty) so it moves only out, never in. To move it in you have to twist a screw.

The automatic cam chain tensioner is known to be a weak point on early GS's.  It broke on my '90 with kind of nasty consequences (chain skipped, bent exhaust valves).  The mechanism has a spiral "watch" spring that turns a threaded rod that tensions the chain slide.  On mine the spring broke where it joins the threaded rod.  With no tension from the spring, the threaded rod worked its way back in . . .  

While it was still running the valves became dramatically louder, and it was more of a slapping sound as the valve springs pushed the cam past the peak of the lobe.  I don't think the chain skipped until the motor was stopped and I attempted to restart it.  Probably a good thing or the damage to bike and rider may have been much worse.

It seems like I read somewhere that the tensioner problem was fixed on later model GS's (~95).