Catastrophic valve problem?

[spots25]

I've got a 01 GS500 that had a problem with a hanging idle. The left exhaust valve was way too tight (couldn't even fit a feeler gage in there). I put one that was too small (about .1 mm clearance) and it ran fine. Now, probably 30 miles later, the problem seems to be back. I'm gonna check it first thing tomorrow morning, but I think I sense a pattern.

My theory: there is a terrible valve problem, in which the valve is somehow elongating at a much more rapid than acceptable rate. This will result in the valve snapping in half, dropping into the cylinder, and making bits of metal come out holes that shouldn't be there.

My dilemma: I want to ride this thing 600 miles back home in a couple days.

Has anyone heard of this happening? What should I do if the valve clearance is indeed too tight once again? What would happen if I dropped a valve at 70 mph?

[robinm]

I would

get the head off it and have it checked out, there is one locally that did the same thing, ended up dropping a valve and totaling the motor, and that is not the first one I have heard of doing the same thing. What you possibly have is a valve recession problem and it will not fix itself, it will just get worse.

[psyguy]

do check the valve clearance(s) again
however, your handing idle may be due to a leak in the intake system

[Craig]

Ride it the 600 miles. If it blows up, I have a 83 1100 ESD I can sell you!

[Nessism]

If you want to know if there is a valve problem, perform a compression check. To measure is to know. Most likely the valve is fine though. It's common for neglected bikes to require shims that are 2 steps smaller than what was previously installed. Most of the time installing the proper shim takes care of the problem.

That said, a hanging idle problem is not likely to be valves - more likely a vacuum leak of some sort causing a lean condition. Pilot screw adjust can also cause the problem if it's too lean.

Good luck.

[spots25]

lol... i probably just worry too much. The valve clearances are fine, and the exact same as I left them. While an intake leak is a definite possibility, it seems unlikely that one developed overnight. I'll play around with it later

[Nessism]

Vacuum leaks can come and go depending on expansion of the parts, humidity in the air, etc. Sounds like you were lucky when it went away for no good reason.

[spots25]

i just rode it around here, and I couldn't get the idle to hang. Seems like everything is in good shape