A motorcycle engine can be considered as a closed system in terms of its operation. In a closed system, the working fluid, which is the fuel-air mixture, remains within the system and is repeatedly circulated to produce power. The combustion process takes place within the engine's cylinders, and the resulting gases expand and drive the piston, which ultimately generates power.
For instance, the engine requires air intake to provide oxygen for combustion and expels exhaust gases as a byproduct. The cooling system also exchanges heat with the surrounding air or a coolant to regulate the engine's temperature. These interactions with the external environment are necessary for the engine to function properly and maintain optimal operating conditions.
So while the motorcycle engine itself can be considered a closed system in terms of the internal processes, its operation and performance are influenced by the surrounding environment, making it somewhat of an open system overall.