The main oil system is the main oil supply system of the carburetor. There are three commonly used main oil system correction (compensation) methods:
● Compensate with infiltrated air;
● Use the oil needle to change the area of ​​the main measuring hole;
● Change the area of ​​the throat and main orifice at the same time.
Motorcycle carburetor (Figure 4)
Motorcycle carburetor (Figure 4)
Among them, the first method is more commonly used. The air compensation method is to add the main air volume hole and the foam pipe between the main volume hole and the nozzle, thereby infiltrating air to reduce the vacuum degree at the main volume hole, thereby controlling the fuel flow and obtaining the required mixture composition. In order to stabilize the composition of the mixture, the float chamber has a through hole that communicates with the atmosphere, and the oil inlet needle valve is controlled by the float to keep the liquid level of the fuel in the float chamber stable. Usually the liquid level is 5-6 mm lower than the nozzle to prevent the fuel from overflowing when the internal combustion engine is tilted. The shape and size of the throat determine the air flow rate and vacuum, thereby affecting the air charge of the internal combustion engine, the fuel supply of the main oil system and the fuel atomization. In order to obtain high-speed airflow for good atomization and at the same time increase the amount of inflation, double or triple throats can be used. The main oil system can only meet the requirements for mixed gas in most working conditions. In special conditions, auxiliary systems are also required.