i have a 2002 zl-500 1400 miles powervalves never been out for anything i,m not realy heavy on the hammer, i use amsoil but on a long trip the sledd started to run very rich no power and would not idle. question is could powervalves be stuck or do i have something else, it almost feels like it is running rich because of a safe mode or something no engine lights lit or pipe temp sensor light on just that it runs real bad but if you shut it off for awhile then start it up it runs ok for a little while then does it all over again.

I am a yammie guy just trying to help but..when & if they stick you will not reach full wot rpm,s. Everything else will seem the same but rpm,s will be way off.

I'm not sure if your sled has the round APV Valves or the blade type valves. My 600 has the round valves. The first thing that I have noticed is a "rattling" noise on easy accelleration, it is usually right about the time the clutch starts to shift around 7000-7200 rpm. This noise almost sounds like a 'spark knock' . The noise goes away when the valves are clean, but after 60 - 100 miles the noise is back. A quick check shows that the valves are starting to hang up.
I just drained all the old oil and filled up w/ synthetic. Hopefully I won't be cleaning the valves as often

If there's no snow in heaven, then I don't want to go

On my 800 EFI, my cables were disconnected. I don't know what caused this, but I could tell that it wasn't runnning right at all. I was getting low rpm's at wide open, and coughing and sputtering at low rpm's. Try this. Start off and stabilize rpm's (30-40 mph). Hit it full throttle. You should notice a definite change in tone in your exhaust (valves opening). If you don't hear this, its time to clean and readjust the cables to the proper length.

Sounds more like ice in the carbs or stuck choke plunger. Remove the choke plunger from the carb, just follow your cable down, clean it and drip a little isopropyl antifreeze down the choke hole. Then try running about 1/3 of a bottle of isoplropyl in your full tank of fresh fuel.

For power valves you can remove the ends of the cables from the servo motor then pull them open by hand. They should move easily and close with a firm snapping sound at the motor.