draining gas

Pull the gas line off the carb and turn the gas on.

^^Yeah. There isn't really another way for the gas to leave the tank, except through an open petcock^^ :D You also have a fuel bowl drain screw on the bottom of the carburetor that you can open. Crack it with a narrow-shank flat-blade screwdriver and let the gas run out through the spillover tube until it stops. This procedure will get rid of all the gas still lingering in the carburetor, even after the actual tank is dry.