Working principle of carburetor

  • The carburetor is actually a pipe, and there is an adjustable plate called throttle plate in the middle of the pipe, which is used to control the air flow through the pipe. There is a constriction called venturi in the tube, where a vacuum will be formed. This contracted part has a metering hole through which fuel can be sucked by vacuum.
  • The carburetor of motorcycle looks very complicated, but as long as you master some principles, you can adjust the motorcycle to the best state. All carburetors work under the basic principle of atmospheric pressure. Atmospheric pressure is a powerful force that exerts pressure on everything. It will vary slightly, but usually there is 15 pounds of pressure per square inch (PSI). This means that atmospheric pressure has a pressure of 15 pounds per square inch for anything. By changing the atmospheric pressure in the engine and carburetor, the pressure can be changed and fuel and air can flow through the carburetor.
  • Atmospheric pressure will diffuse from high pressure to low pressure. When the piston of the two-stroke engine is at top dead center (or the piston of the four stroke engine is at bottom dead center), a low pressure will be formed under the piston in the crankcase (above the piston of the four stroke engine). At the same time, this low pressure will also cause low pressure in the carburetor. Because the pressure outside the engine and carburetor is relatively high, air will rush into the carburetor and enter the engine until the pressure is balanced. The air flowing through the carburetor will drive the fuel, and then the fuel will mix with the air.
  • Inside the carburetor is a pipe. The throat is a constricted part that forces air to accelerate through the carburetor. The sudden narrowing of the river can be used to explain what happens in the carburetor. The river will speed up as it approaches the narrowed bank, which will be faster if the bank narrows continuously. If the same thing happens in the carburetor, the accelerated flow of air will cause the air pressure in the carburetor to decrease.
  • The gasoline enters the carburetor from the fuel tank through the gasoline filter, which can filter out the impurities mixed in the gasoline and the oxide scale in the fuel tank. If the quality of the filter is defective, some impurities will enter the carburetor through the filter. In addition, gasoline contains components that can form colloids. After long-term deposition, colloids will condense and adhere to the surface of carburetor parts (such as measuring holes), oil passages and float chambers.
  • The air enters the carburetor through the air filter. Considering that the intake resistance cannot be too large and other factors, the filter device cannot be too dense, so some minor impurities in the air will still enter the carburetor through the air filter. If the quality of the filter is defective, it will cause more serious impact.
  • Many components that make up the carburetor's oil and air passages, such as the main orifice, idle orifice, main air orifice, idle air orifice, main foam tube, etc., have holes with small inner diameter (inner diameter is between 0.3 and 1.5mm). Gasoline impurities, colloids and impurities in the air entering the carburetor will often change or block these holes, resulting in poor carburetor's air and oil passages and changes in carburetor's oil supply characteristics, Even cause carburetor performance failure.