The function of the exhaust pipe universal drum is to exhaust the exhaust gas and change the characteristics of the engine according to different universal drums. In the exhaust system, due to the inertia force, the vacuum pump low-pressure belt will appear after the exhaust gas and rotate to the engine outlet, and the vacuum pump low-pressure belt will rotate with the valve. If the duration control is close to the end of the exhaust process, the inlet valve has been opened and started to intake, that is, when the exhaust valve and inlet valve are opened at the same time, the low-pressure belt of the vacuum pump will open the exhaust port and inlet port at the same time due to the suction of the vacuum pump, the low-pressure belt of the vacuum pump will be discharged due to the suction of the vacuum pump, and the fresh mixture will be sucked into the cylinder, so as to improve the intake efficiency of the engine. For a 1000ml motorcycle, 70% of the actual intake efficiency is also good under the condition of 10000r / min. Because the exhaust valve of the engine can not completely exhaust the exhaust gas in a very short time when driving at high speed, the inlet valve can not fully intake air. The inertia force and low air pressure produced by this kind of exhaust are of great significance to improve the characteristics of the engine.