On the fuel tank switch of the motorcycle or on the fuel tank cover next to the fuel tank switch, there will be a spare fuel tank mark. If it is a graphic, it is a half-cup of water mark. If it is a letter, it is usually RES, oil, oil. There will be an arrow on the handle of the switch. Pull the handle of the fuel tank switch so that the arrow points to the graphic of a half glass of water or the RES letter logo, which is the spare fuel tank. On most motorcycles, when the handle is turned upward, it is the spare fuel tank.