Yup, I'm not thinking it's the power valves, sounds even as simple as a pinched fuel line. Pull the carbs and clean them good, check all the fuel lines for cracks and if they're brittle, replace them. Nothing worse than loosing gas because a fuel line has a slight leak.sambell said:power valves controll high rpm, I would clean the carbs and put a new fuel filter on.
The famous Arctic Cat stator would be my guess.zr440man said:i got a 1999 zr 440 sno pro when i start it up it will be ok for a few seconds but when i get it up to like 3000 rpms it will just drop down to 1000rpms if you dont get it in time it will die. does eny body know what this is.