Hanging Idle 73 z1 900

Hi all new member here
i have a 73 z1 all stock have an issue with hanging idle
it will stay at 2400 rpm then drop to normal idle 
new intake rubbers
carbs ultrasonic cleaned vacuum balanced
could choke assembly be causing the problem original seal rubbers or any other suggestions  ?
thanks in advance
Mike

Mike there are two distinct different "types" of hanging idle. One being a leaking manifold other being an over-rich condition but burning it off slowly keeps idle too high. A vacuum leak doesn't generally go away, over-rich does. Double check your fuel level first. If choke plungers, i have a trick for that too. These ramp style carbs are finicky to start with and any glitch in the array of multiple springs/seats/levers can make things worse. Also if carbs have been "gone thru" make sure the jet holders haven't been over tightened. I warped, even slightly can grab the slide jet needle and keep it's slide from fully seating. Keep us informed.     

No mention of synchronization of the carbs? Did you sync them. Never mind I see you balanced them. What tool do you use.