101 Motorcycle carburetors look very complex, but with a little theory, you can tune your bike for maximum performance. All carburetors work under the basic principle of atmospheric pressure.
Atmospheric pressure is a powerful force which exerts pressure on everything.
By varying the atmospheric pressure inside the engine and carburetor, we can change the pressure and make fuel and air flow. Atmospheric pressure will force high pressure to low pressure. This low pressure also causes a low pressure inside the carburetor. Since the pressure is higher outside the engine and carburetor, air will rush inside the carburetor and engine until the pressure is equalized. The moving air going through the carburetor will pick up fuel and mix with the air.