Terrifyingly fast GS idle... HELP!!

[Von Vester]

Leaking intake pipes is a very strong possibility and I agree that needs to be checked. However, if you discover that your intakes are not leaking I have another suggestion that caused the same problem on my GS.

When I first got my '93' GS used it had the same problem with high idles after warm-up. After much searching I discovered a missing part within one carburetor, a small spring seat that falls out when the carb is opened. Evidently the last person to work on the carbs didn't notice which tool box it rolled under when it fell out and just reassembled the carb without it. I cannot emphasize enough how easy it is for this part to fall out without being noticed, so this is a good possibility if your carbs have ever been opened by an amature mechanic.

You can test if this is your porblem very easily by waiting for the problem to occur and then peck lightly on the side of each carb with a screw driver handle and see if the RPM drops. If the RPM does return to normal then that means the needle valve is at the whim of gravity and isn't being pushed on by the needle valve spring, i.e. the spring seat is missing.

When I purchased the new spring seat ($3.50) and installed it, all my engine problems disappeared, including the plug fouling I was getting every 300 miles or so. Now my engine runs flawlessly with all original jets and settings. Without the spring seat the engine performance is tolerable but not smooth and has a lot of quirks.

Good luck solving your problem.