Is it a diaphragm problem?

[Lucky_Lou]

Suddenly playing up after rebuild......tickover is fine but some times the throttle isnt shutting down kepps revving at about 3000 and sometimes when accelerating theres a pause before both cylinders kick in then it goes like a rocket  i suspect a sticking diaphragm anyone else got any sudgestions.
Lou

[ukzknos]

Did you rebuild the Bings?
If so, is the main jet and needle in line?
If not the piston will not fall to the throttle shut position.

[montmil]

If, in rebuilding the Bings, you removed the butterfly valve from its shaft, it may be hanging up in the carb body.

I read a recent article about this same problem. The NA Bing agency suggested removing the carbs and, while shining a light into one end, looking for interference between the butterfly and the carb throat.

The suggested cure was to loosen the two screws securing the valve to the shaft -I'm sure you 'staked' them to the shaft and reposition the butterfly valve so it doesn't drag against the throat interior.

Hopefully, this may help.   Monte

[drewboid]

Are you sure the throttle plate isn't closing? sometimes not returning to idle is caused by sticky timing weights. Have you tried putting the bike in gear and slipping the clutch to bring the RPNs down? If they then stay down I would investigate the timing. Good luck!

[Bob_Roller]

After seeing the opening sentence, suddenly after rebuilding, would lead me to believe, that it was something that you did during the rebuild process and reinstallation, that may be the problem, you need to go back and look at everything you did.

Remove the cables from the carbs, and see if you can get them to hang up, check the cables for routing and proper installation.

High rpm's after a carb synchronization, can be the result of not having the engine up to operating temperature when the adjustments are done.

[Lucky_Lou]

Are you sure the throttle plate isn't closing? sometimes not returning to idle is caused by sticky timing weights. Have you tried putting the bike in gear and slipping the clutch to bring the RPNs down? If they then stay down I would investigate the timing. Good luck!

when i slip the clutch the revs drop and stay down this is an intermitant problem and not giving me as much consern as the accelleration issue.Im away till after easter and will strip the carbs when i get back i will check the needle valve and butterfly again thanks for your input
Lou