It is generally recommended to store your motorcycle with a full tank of gas.When the gas tank is full, there is less room for air and less oxygen in the tank which can help prevent the formation of condensation. Condensation can lead to water contamination in the fuel system, which can cause rust and corrosion.Additionally, when you store your motorcycle with a full tank of gas, it also helps to protect the fuel system by keeping the internal parts coated in fuel. This can help to prevent the rubber seals from drying out and cracking.However, it is important to add a fuel stabilizer to the gas tank before storage. This will help to keep the fuel fresh and prevent it from breaking down, which can cause damage to the carburetor or fuel injection system.If you can't fill the tank, you can also drain the fuel tank as much as possible, run the engine until it stalls, and add a fuel stabilizer to the remaining fuel. This will help to prevent the fuel from breaking down, and also reduce the risk of moisture entering the tank and causing rust.