I have been working on getting a 92 GS500 that I recently purchased back into ridable shape.  The bike has a little over 16k miles.  The chain and sprockets clearly needed replaced, so I ordered the parts.  When I went to install the front sprocket, I found that the original sprocket was very loose and could wiggle around quite a bit on the shaft.  The new sprocket is a little tighter.  I can't see it rotate separate from the shaft, but I can definitely wiggle it.  The best explanation I can give, is if you hold the top and bottom of the sprocket and push on one while pulling on the other, then it angles the sprocket and moves the teeth at the top / bottom of the sprocket in / out between 1/16th and 1/8th of an inch.  There is also a little bit of room between the snap ring and the sprocket, so it can move in and out on the shaft.

My question is how to tell whether the drive shaft is too worn to be usable.

Thanks

-Greg

Some slop is normal (at least side-to-side).  GS500s have a floating front sprocket.

-b.

The real way to tell if the shaft is worn, is to remove the sprocket and inspect the splines on the shaft.  Any noticable notching is bad.  As far as a wiggling sprocket, some manufacturer's tolerances are not as tight.  I would conjecture that even a Sukuki OEM sprocket may not be any better.