I never paid attention to it before, but I just redid my carbs and now it take about a second for them to close completely under their own force when I let off the grip, I can still force them closed by twisting the grip forward, and they never say open, even with the bars all the way to the right.

 

It should snap right back.. check to be sure that teh cables are not kinked.... you couldn't hurt it by lubing them up, but if it happened suddenly check how they are routed...

Adam

 

It turned out to be the cable tension, I tried putting it to the tight end of the specs, because I hated moving the throttle almost a quarter inch before it did anything, but that causes it to not snap back. I ended up having to give it over an eighth, but that did it, thanks for the advice.