Will not return to Idle when driving

[mech210]

I am having a problem with my 1980 750f. In the shop I can get it running like a champ but when I take it on the road the Idle wants to stay at about 3000 and then slowly come down. The hotter the engine the longer it wants to stay high(sometimes upto 3min). but then when I am working on it I can not recreate the problem. The bike was sitting for 5 years before I started working on it. I have cleaned and adjusted the carbs and it runs amazing when it is on a stand but as soon as I take it out on the road the problem starts again. Does anybody have any ideas?????

[Re-run]

Air leaks are a common cause. Many times it is the manifolds between the carbs and engine. They get really hard and do not seal well or develop cracks.
My 78 did this after a long ride. When normally warm, it idles about 1100 or so +- tach error. After a couple hours, it would idle at about 1500 for a bit. So no big deal. Yours though may be from hard manifolds.

[mech210]

The boots seem to be good but I will check them again. I was looking at something else. It seems the mechanical advance is hitting max at 3000 rpm instead of 6000. I am going to try another to see if it makes a difference.

[Re-run]

Unless someone messed with it, your advance should be hitting stops. But that would affect the bike even when cold.