Try this when the engine sticks at a high RPM idle:
Select first gear, keep the bike a standstill with the brake, apply clutch pressure enough to load the engine forcing the idle RPM down.
Then you pull the clutch again to see if the RPM stays low or increase again.
If the RPM stays low I would say you most likely have leaking carb trottles (the extra airflow leaking by the trottles allows the engine speed to stay high until you load the engine).
When the idle went up (around 1800), I loaded the engine and the idle came down and stayed down. So if it is the carb (in my case, a single 34mm Makuni), is it leaking internally or would it confirm that it is the carb if I use starter fluid spay to see if the revs increase? The story behind my bike/carb is that the PO (a Norton guy) had not sealed the fiberglass tank and the carb had stuck open on him a few times. I sealed the tank and completely cleaned the carb slide and throat. Works fine except for the idle issue. There is definitely a tight bend in the cable after it leaves the carb. It is an Interstate so there is lots of tank over this whole area. I don't quite understand the carb sleeving option since I understand that the slide must be a precise fit. Thannks for any help.