Motorcycles with a reserve mechanism typically have a fuel tank with two separate compartments: the main fuel tank and the reserve fuel tank. The reserve fuel tank is intended to provide an additional amount of fuel when the main tank is nearly empty, allowing the rider to reach a nearby fuel station.
When the motorcycle is running on the main fuel tank, fuel is drawn from the bottom of the tank where the fuel supply is located. As the fuel level in the tank drops, a fuel reserve pipe or tube extends deeper into the tank, reaching the reserve fuel compartment.
When the main fuel tank reaches a critically low level, usually indicated by a low fuel warning light or a reserve position on the fuel petcock, the rider can manually switch to the reserve fuel supply. This is typically done by either turning a fuel petcock valve to the reserve position or flipping a switch on the handlebars, depending on the motorcycle's design.
Once the rider activates the reserve mechanism, the fuel flow is redirected from the reserve fuel compartment through the fuel system to the engine. This allows the rider to continue riding for a limited distance until the reserve fuel is depleted as well.
It's important for riders to remember that relying on the reserve fuel should be a temporary solution to reach the next fuel station. It's recommended to refill the main fuel tank as soon as possible to avoid running out of fuel completely, as this can lead to an unexpected breakdown and potential hazards on the road.