1981 Yamaha XJ550RH High rev issue

Just recently acquired an xj550, rebuilt the carbs and fired her up. The bike is running pretty smooth for the amount of time it has sat (17 years). I have been experiencing an issue with high rev. Whenever I rev the engine (3-4k) it refuses to come back down UNLESS I press down on the carb assembly. First thought is either the throttle is not snapping back all the way, or potentially a vacuum leak. Any thoughts?

 

I am having the same pro lem with mine. If you figure it out please let me know! I will do the same.

 

Vacuum leak is always suspect when the rev's stay up, but since you report that pushing down on the carb assembly effects it, it could be your linkage not moving through its motion fully, or the grip is holding it open, cable is binding, or your carbs still need attention. Have you tried adjusting the idle screw counter clockwise to lower the idle speed? When you say rebuilt the carbs did that include breaking the rack and replacing all the wear parts? After 17years if they weren't drained and fogged then they are due for a full overhaul.