Among the various functional devices of the carburetor, the main oil supply device is the oil supply device required by the engine in various other working conditions except for idle speed, and is the basic oil supply structure of the carburetor. The idle speed device is a device that provides a small and rich mixture at idle speed to maintain a stable minimum speed of the engine. The enrichment device is an additional oil supply device when the engine is under heavy load to make up for the lack of the main oil supply. The acceleration device is a device that supplies additional fuel when the throttle opening suddenly increases when the car accelerates, so that the engine speed and power can be rapidly increased. The starting device is a device that provides a very rich mixture when the engine is cold started. The common method is to install a choke in front of the throat to control the intake air volume.