Flying Horse 2-Stroke/4-Stroke Motorized Bicycle Engine Gas Tank Threaded Fuel Valve &ndash; Gas Bike Fuel Valve Replacement The Fuel Valve turns the fuel on and off from the gas tank on any 2-stroke or 4-stroke bicycle engine kit gas tank Installation is a breeze: from the bottom of your tank, uninstall the old fuel valve, and thread the new valve in to the gas tank. Attach your fuel line and you're ready to ride