has been rebuilt and runs good, choke works great. only thing is when after running on the highway at 70-80mph it will idle about 1050rpm. normally have it set about 750rpm. after about 10mins it will come back down, what should i look for? when i rebuilt the carb i backed out the m/c solenoid about 4 turns, i dont have a dwell meter to set at this time

 

Linkage is more than likely sticking. Clean it real good with carb cleaner and then spray it down with WD40. If that doesn't work then the linkage might have to be "adjusted" a little. My old one would do that and I noticed that the secondary linkage wasn't coming back all the way when I would let off. If you work the linkage by hand, you'll see what I'm talking about. It can be bent a little if needed to make it close fully.

 

Yes, check the throttle when it is acting up. The M/C controls the air:fuel ratio, not idle speed.