Why wont the Carburetor on a 2001 Arctic cat take adjustment?

500 4x4 Suzuki motor. You can screw the adjustment screw all the way in and nothing happens... also with the air box off completely off, you can rev it to a high RPM and a mist of gasoline comes out the back of carburetor. runs a lot better with the air box off and it smokes black a little bit. any help? thanks