My quad sat at my dads house for awhile (3 months) and I took it back to my house and cleaned the air filter,changed oil and changed the coolant. I've noticed it starts right up no problem with the choke on back right as i take the choke off it dies. I heard it idle then clank and dies. I does have bad jetting (runs really lean) cause i took the spark arrestor out of the pipe so i have new jets to put in it but before it still would start up and run without the choke. When i bought the quad i've also noticed that the fan has NEVER came on at all.
did you buy it new or used? and is the pipe stock? and did you try running it with the air box lid off ? or did you mess with the air mixture screw on the bottom of the carb at all? look at the top of page one, great write up on jetting issues.