I have a similiar problem to Boscoe53.  It starts up okay with full choke, and after warming up a little can take the choke to half.  As soon as I try to throtle, it snaps, pops, clunks and won't stay running.  Have to choke it constantly to keep it running.  Have increased idle speed and changed the gas, but it still won't stay running without choking.  

Turn the gas off, get a clear jar, hold under carb, and open the bowl drain screw.  There may be a hose leading down under the skid plate, so the gas may come out here.  Look for water in the fuel in the jar.  The water will be beneath the gas.  If its water in your tank, it goes to your fuel bowl.  Choking draws more gas into the carb, which flows over the water, and into the cylinder.  If no water is found, a good carb cleaning (dissasembly, not some XMart pour in stuff) will probably do the trick.  I use a good fuel stabilizer year round, and seldon have problems like this.  Some of my buddies say it cost too much to add stabilizer year round.  Price a carb cleanup on a new twin carb Kawasaki, and you'll buy stabilizer too!  

turning the gas valve on your tank and letting the atv run until it runs out of gas will help keep the carb from getting gunked up when you are not riding it.

cleaning the carb is easy if you learn to clean it you can have it done and ready to ride in about 15 minutes.
stabilizer is good too, but cleaning it out yourself it completely free.