1995 750SS Desmodue Idling Problem

Hi all, I’ve refurbished a 750 Desmodue for a friend and am having problems with the carbs.
The synchro mechanism has been correctly set, carbs are as clean as they can be, diaphragms are good, cables are new & free. The butterflies snap back cleanly.
So, when trying to get the bike to idle, if I slacken the idle screw until it has no influence, the bike won’t idle but it revs freely and drops back quickly.
I need to turn the idle screw quite a way in to be able to get it to idle but when I blip the throttle, it revs to 3000+ rpm and is reluctant to return to idle.
We’ve looked at EVERYTHING including possible air leaks.
The thing that throws me is the fact that it runs so sweetly when it won’t idle !!
Anyone come across this and cured it ?

Hi David,
I’ve owned on of these bikes and had similar problem. I found taking off throttle plate on bike where cable goes around off and cleaning it thoroughly and behind it helped Also putting some carb cleaner in tank and going for long ride going through a range of high, medium and slow speeds and acceleration helped a lot. Other than that could be electrical ht leads, plugs, pick ups on flywheel ect.