Gas supplementing structure of motorcycle engine

The invention provides a gas supplementing structure of a motorcycle engine, and belongs to the technical field of motorcycles. The problem that direct leakage exists when secondary purification is conducted on tail gas of an existing motorcycle is solved. According to the gas supplementing structure of the motorcycle engine, the engine comprises a cylinder head with exhaust passageways, the gas supplementing structure comprises gas supplementing passageways formed in the cylinder head from top to bottom, the upper ends of the gas supplementing passageways communicate with the outer portion, the lower ends of the gas supplementing passageways incline towards the inner ends of the exhaust passageways, and lower end ports of the gas supplementing passageways penetrate to the top walls of theexhaust passageways. A flow guide protruding part protruding downwards is arranged on the top wall of each exhaust passageway, located between the lower end port of the corresponding gas supplementing passageway and the inne