PETCOCK

A small valve or tap which is used to control the flow of liquid. You may find one at the bottom of a radiator to permit draining the radiator. A petcock may also be found on the line coming from the fuel tank in small engines and motorcycles . It allows you to cut the flow of gasoline going to the carburetor . On some motorcycles , the position of the petcock lever may permit draining the last part of the fuel tank as a reserve position. In units where the carburetor is fed by gravity feed from a fuel tank , turning off the petcock when the unit is not in operation may prevent gasoline from leaking past the carburetor's needle and seat and into the crankcase to dilute the oil.