High idle when warm

[Revjoel]

My '80 GS550 runs fine but once i've ridden it for 30 min or so and the engine gets warm/hot, it idles very high (around 2000-2500). It doesn't do this all the time. Only when it's warm outside.
Where should I begin looking for problems? My first thought was the o-ring gaskets at the carb intake. Maybe they are softening up and creating a gap when warm?

[Steve]

Not so much "softening up", they probably have a gap to start with.

What are the settings on your pilot screws? If they are set too lean, you might get the same symptoms.

.

[Revjoel]

Being a new rider, I'm not certain how to even check the screws.

[bccap]

When I had the same problem { high idle after bike is fully warmed up } it turned out to be the carb boot o-rings as you suspect. To check out what Steve is referring to give Ed's excellent carb cleaning tutorial a read. Pretty much everything you need to know is in there.....

http://www.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf