Was riding my 2004 450es. After 10 minutes of riding about 30mph. The ATV lost almost all of its power. Slowed down and shut off. Kind of limp mode. Any idea? 85 degrees normal day.It turned back on with no problem. But I drove it very slow back to the garage about 200 feet from where it cut off. I did smell something burnt a bit, I guess...What happened, what to do next? P.s when I turned the switch key back on (in the garage), the cooling fan wasn't working. Not sure if it's broken and caused overheat. Or wasn't working because engine temprature was ok.

 

Has it any oil in it? Sounds a bit like a seizure. If by "vent" you mean the cooling fan, it will only come on if the engine is still hot enough. You can check if it is working by removing the wire from the sender unit and touching it to earth with ignition on. The fan should then run, though this doesn't tell you if the sender unit is OK. That can be checked by removing it and testing it, in almost boiling water there should be continuity between case and wire connector, but no continuity when it is cool.