When I go to start my atv up, it doesn't want to stay started. If the choke is on it will run but once I let the choke off, it dies on me. Can anyone point me in the right direction as to how I can fix this problem?

 

Pull the spark plug and check to see if it is black or clean. It may need replaced. I had that same problem with my 2, brand new 07 and 08 TRX 500's. They had sat in the show room and only been started to move in and out of the building at times and fouled the plugs. Not sure what kind yours takes, but I assume possibly the same as mine. Check at Advance Auto Parts. Here in VA i can get mine for around $8.00 as opposed to the dealership of $15.00 plus a 50 mile drive. Try this and see what it does and let me know. I still have to do this same thing to my 07 till I get a new plug....

 

If it doesn want to run, with the so called choke off...the pilot jet is plugged. The choke is really an enrichener, so it provides the gas when its on (it doesnt strangle the air like a real choke does), both accomplish the same thing, one cuts air, the other adds gas. But when you shut off the choke, the gas it provided is blocked off, and the pilot jet isnt taking over, probably due to dried up gas in the small jet. Just remove the pilot jet, look thru it like looking theu a telescope, and if you cant see light coming thru the center hole....its plugged. Just go buy a new one.
Then make sure from now on, that the float bowl is left dry, when you let the quad sit for more than a couple of days. Just turn the gas valve to off, and keep running the motor til it dies. This leaves the bowl dry. Next time you start it....the jet wont be plugged. If you do this all the time, chances are itll never plug again.