Yes, it is generally recommended to turn off the fuel on a motorcycle when it is not in use for an extended period of time. By turning off the fuel supply, you can prevent fuel from flowing into the engine and potentially causing problems such as fuel leakage or flooding.
When you turn off the fuel supply, the motorcycle's engine will eventually run out of fuel and come to a stop. This is particularly important if you're storing the motorcycle for a long period, such as during the winter months or if you won't be using it for several weeks. It helps prevent fuel deterioration, clogging of the carburetor (if equipped), and other issues that may arise from fuel sitting in the system for an extended time.
Additionally, if your motorcycle has a fuel petcock (a valve that controls the flow of fuel from the tank to the engine), turning it off will prevent any potential leaks from occurring if the petcock or its seals become faulty.
Remember to consult your motorcycle's owner's manual for specific instructions on how to turn off the fuel supply properly and safely, as different motorcycles may have different mechanisms or fuel systems.