I agree with Shibby. I ran into a similar problem with a friend?s bigbear so we opened up the carb to find a sold layer of green crust. After pulling and cleaning all of the jets and the bottom of the float bowl with carb cleaner we put it all back together, drained her tank, filled it up with new gas and it fired right up and ran like a charm.
Moral of the story, don't leave your quad sitting for more than a few months without turning the petcock (fuel switch) off and letting the quad run out all of the gas in the carb.
btw, my friend swears she put fuel stabilizer in her tank but she let it sit for over a year without trying to fire it up so if she is correct even the stabilizer failed after a year without a start.