My 2000 Sportsman 500 has started doing something weird when I'm warming it up. It always starts right up, no matter how cold it is (usually 0-30 degrees this time of year). I let it sit and idle to warm up while I'm getting all my gear on. If it sits idling long enough (5+ minutes), it will gradually start idling slower and slower and rougher and rougher and then die. It does this whether I never touch the gas, or if I rev it up a bunch. It will start right back up, but will die again if I let it idle too long before riding it. Once I get on and ride awhile, it will idle forever and not die. There are no ATV trails around here in the winter (they are all designated snowmobile trails between Thanksgiving and spring thaw), but I start it up and ride it a few miles on the back roads at least twice a week, and it just started doing this about 3-4 weeks ago. Other than the idle problem, everything else is OK, and it runs fine while riding. I bought it used in October and it was just serviced at the dealership in November....oil & filter change, lubed, air filter replaced, etc. They couldn't find anything wrong with it then and even commented on how clean and well maintained it was. Any ideas?

 

stupid question, but did u try turning up the idle a little. my 02 did the same thing, it would load up w/ gas sitting their and then not idle good, more then likely because of the cold air and being jetted for a little warmer temps.

 

Change your plug, reset your idle and fuel mixture, and you should be all good.

 

try and turn your air mixture screw out some and see if that helps. it sounds like it is chokeing itself with the cold air and when you ride everything heats up and warms the air as it enters....