Running on..... Revving the nuts off it

[I_Duddits]

So here's the problem. I start the 5 hundie, the usual brrrrrr, pop brr, bang, brrrr, nice idle. Give her a twist of the throttle and let go........ The revs she no drop down back to idle, instead the revs scream through the roof at which point I s**t my pants and press the kill switch. The throttle action is sweet, no sticky points keeping the throttle open, oh no, she snaps back nicely.

Any ideas?

[kx500af]

check the easy stuf first is the slide in the carb falling all the way closed air fuel mix screw (two turns out)you could be sucking air check for cracks in the read valve boot gasget for read valve or left side crank seal hope this helps

[kaw rider]

was your gas turn on. it's fuel or slide problem

[I_Duddits]

I have a spare carb, thinking of replacing it and give her a run see. I'm thinking it might be air somehow.
The bike's a motard and bloody noisy, the neighbors...... they doth protest to my constant testing 

[elfoleyo]

I had somthin kinda like that happen when riding once.. I took the carb apart to find that the tab on the slide that the Idle screw sets on had broken off. It kinda wedged its self insuch a way as to keep the juce on. kinda scary.

[iamsofaking]

Mine had the same problem.  The needle on my slide turned out to be bent.