The Cb400 valve is a little rough.

Maybe the oil circuit is blocked. The throttle is dirty.

The connection between spark plugs is too big. It is recommended to clean the oil circuit and throttle. Change the spark plug. The reason why the motorcycle fuel filler door is stuffy and powerless: 1, the carburetor has a lean mixture, and the mixture knob can be adjusted; 2. The carburetor is dirty. In this case, the carburetor needs cleaning; 3. The dirty air filter affects the air intake, so you can change an air filter; 4, spark plug carbon deposition caused by insufficient ignition energy, the treatment method is to clean the spark plug. Motorcycles are two-wheeled or three-wheeled vehicles driven by gasoline engines, and the front wheels are steered by handlebars. It is characterized by lightness, flexibility and fast running. Widely used in patrol, passenger and freight transportation, and also used as sports equipment. Motorcycles are divided into street cars, road racing cars, cross-country motorcycles, cruise cars, station wagons and so on.