Over Revving

[Lucky_Lou]

My Brothers 81r65 has got the better of him and hes working away so doesn't get much time to sort things out. Ive offered to give it a once over the main issue is it over revving once it has warmed up.
He recently did a full rebuild on the carbs when there was found to be an issue with one of the butterflies that in mind i road it home this morning leaving Gertie with him to play with.  
Sure enough once warmed up the revs were sticking at about 2500 i put it on the center stand and had a feel at the butterfly shafts to see if they were sticking.
I felt the left carb blowing from the rubber joint to the head, these are the original rubbers so i suspect thats the main problem.Being an 81 it has electronic ignition something i have no experience with as mine is a 79 with points, am i right in thinking the timing is adjusted the same by turning the bean can assembly? i may try this in different positions if the rubbers dont cure it after ive checked the valve clearances.
If theres anything else worth checking out let me know..
Ta Lou

[Justin B.]

Timing is adjusted the same on all beancan models.  Were the revs hanging BEFORE he jacked around with the carbs?  An air-leak between carb and head could cause idle speed to increase as can binding cables and sticking advance weights in the bottom of the beancan.

[Bob_Roller]

Seeing as how the carbs have had major work done to them, I'm inclined to to believe that the issue lies there, I'm assuming this wasn't happening before the carb overhaul .

If it isn't a carb tuning/adjustment, about the only other possibility is the centrifugal advance mechanism in the 'bean can' is sticking .

Yes, you adjust the timing by turning the 'bean can' .

[montmil]

Lou, there's a possibility that the idle air/mixture screws were tweaked before the bike was fully warmed up. They may be turned out a bit too far. The two small screws make for big idle rev changes.

You may have to pay a ransom to get Gertie back home.

Monte

[Lucky_Lou]

I don't have my Haynes manual with me so...how big a job are the advance weights as i recall this wasn't an issue before the carb rebuild but has surfaced intermittently since.
Lou

[Julio A.]

My 81' also had over revving problems before.

It idles at 2500rpm.

I found that the ring clamp securing the rubber between the head
and carburetor was loose, letting air in and making the mixture lean.
I tightened it and fixed the problem.

After a 15 minute warm-up run, It idled at more than 3000 rpm.
After consulting with my Dad, he messed around with the Fuel mixture screws and the problem disappeared.

This makes me believe that it may be your carbs that have a problem.
Or maybe throttle cables sticking  

[Barry]

Much more likely to be the carbs than the advance weights.

You can do a test for advance weights. In gear put the front wheel up against a brick wall and put some load on the engine until the revs drop. If the revs are inclined to stay down its likely the advance weights if they rise again quickly it's more likely carbs. Wish I'd done this test before diving into the bean can.