Any help is greatly appreciated, I have a 2003 400 4X4. Out riding and after approx 20-30 minutes the machine heats up and shuts down, can not get it started until it cools back down. This happens when it is warm outside, in the winter while plowing it runs great and stays running. I have approx 800 miles on the machine.

 

It could be that the engine is running lean or rich causing the overheating , it could also be that the valves need ajusting ; or it could be a vapor lock in the gas tank vent hose i would check the vent hose first then move on to the valves and carb !.......

 

I agree with Williebee in that is sounds like the engine is running lean and it may need to have the valves adjusted.
Just as an added thought you may want to check the oil-cooler (radiator) and the hoses, if these are obstructed then the oil can't circulate and it could cause overheating.

 

Thanks for the sound advice, I will get on these checks, thanks for your time.

 

I agree a lean running engine will run a little on the warm side.

My question is why is it shutting off by itself? As far as I know a 2003 AC 400 does not have an auto-temp shutoff OR low oil shutoff? I know it does have an engine temp light, a temperature sensor that turns the cooling fan on/off but that's it.

Does the cooling fan turn on after it heats up a bunch or idles for a long time?

I had an old suzuki ATV that did as you described. It ran fine for about 10-20 minutes then shut off like you had hit the kill switch. No matter how much you pulled the pull start or cranked the battery it would not run. But, inthe winter plowing snow it worked fine. I discovered that something was wrong with the CDI (little black expensive little box). When mine shut off if I poured cool water over it it would start right back up and run fine until it heated up again.

My experience has been (I had an oil issue a few years ago) that the engine will run HOT right up until it seizes from improper cooling. So I am pretty sure it shutting off and restarting later is some kind of electrical issue either the Coil, CDI or something like that. There are tests for these in the Service manual.

SJ