This ONLY happens at operating temp. Let the bike cool down. Idles fine. At operating temp I can come to a stop, clutch the idle down from 3.2 to 1.2K (where I have it set 'normally') and then blip the throttle back up to 4K and the idle 'sticks' again at 3.2k.
If I recall correctly Svejkovat, I had that exact problem initially which was masking the weak bean can springs. I'd caused the sticking at high revs (mine was approx 2.4K) by throttle stop screws being too far in, affecting the idle air flow with the butterfly valve being slightly open at idle.
Once the idle speed is adjusted to the correct range (900-1100rpm) with a
hot AND recently tuned engine (including head nut torque, valve clearances and timing), if the rpm stays high after blipping the throttle or riding over 4K rpm but is able to be bumped down to idle by the clutch I think the bean can needs to come off for an inspection and lube. It's not too hard to take apart and put back together, you will really only be looking at the weight arms and pivots once in, as well as giving the shaft bushes a grease.
Buy some new fly weight arm springs first (Motobins sell them) and a proper 4mm pin punch, not just a nail punch.
Here's a link to my long winding path along a sticking bean can problem.
http://www.bmwr65.org/YaBB2.612/cgi-bin/yabb2/YaBB.pl?num=1504037694/0