High idle, some time?

[Concrete Mike]

2007 800, when going down the trail over 7000rpm and i back off the revs stay up to 5000.With brake on they will drop to engagement revs.Problem had got slowly worse last spring till crank broke.I now have new shortblock,stator ,flywheel , throttle cable and carbs cleaned.The only way to slow the motor
is to choke it,then it idles fine.The problem also seems worse at lower elevations.I have already gone with bigger pilot jets but seems no different.
any ideas thanks Mike

 

[sledsrock]

Sounds to me like a big vacuum leak.

 

[Concrete Mike]

took the top off of the carbs and found the little spring had broke and was stuck in the linkage.New springs installed and seems all better.