I have a '91 gs500 with about 35k miles on it, and when it hits 3.5k+ RPM a ticking noise begins... the noise actually seems to fade at around 4.5k RPM but if I lean in forward, I can still hear it. It sounds like it's coming from the instrument cluster but it could just as easily be the front of the engine. Disconnecting the tach doesn't get rid of the noise.

The ticking mostly happens under load - revving it in gear 6 on the stand may make the noise, but not loud enough for me to identify. It's easiest to hear under load in gears 2 and 3, particularly going uphill. When I'm riding on flat ground it's still there, just not as loud. Giving it more gas increases the volume, less does the opposite. It still makes the noise in higher gears, it's just hard to hear over the wind.

Fairly recently I replaced an exhaust valve and did the valve shims, and changed the oil. The ticking developed shortly (not immediately) after that was done, so I think that has something to do with it. I don't think I noticed it until something along the lines of 400 miles after I did the work.

I generated a click track in an audio program at 1000 clicks per minute and it seemed to match the frequency the engine was making noise... so ~1/4 the RPM, maybe a single valve.

I'm trying to avoid an unnecessary teardown; I'm fairly confident in my skills to rebuild an engine but it's currently my only transportation.

So: Generally, it seems to point to valve noise - but would it be normal for it to only tick in a certain rev range, and get louder under heavier load?


TL,DR: Ticks at 3.5k+ RPM, seems to come from front of bike, developed ~400 miles after valve work and oil change, ticks louder under heavier load.

What you will find with the GS is that it is a noisy bike. If you recently did some valve adjustments it could be them. It doesn't mean it is bad if it makes a noise as it usually means they're happier.

I would be re-checking your valve clearances.
It is possible that the new valve you replaced has now bedded in and clearances have changed.

I figured that the new valve could have worn in, but I would imagine that would make the clearances tighter - If it seated in farther the stem would stick out more and hold the bucket closer to the cam, no?