I have a 1997 King quad 300 that will not start unless you drain all the gas from the carb and pull start it, it had a carb rebuild last year and was running and starting fine until recently. It seems like it's getting way to much gas.

 

I have a '96 and have never had that issue. I just had to replace the fuel pump on mine to get enough fuel to the carb to burn.

Does the carb have a standard float valve that could be worn out and letting it flood the carb with fuel?

I know on my sleds the float needle can get worn and it won't seal the fuel off completely.