What is the function of the carburetor needle height?

[LaAdriana]

The function of the carburetor needle height is to form an annular main nozzle with the carburetor main jet, delivering a certain amount of combustible air-fuel mixture to the cylinder head. Below are the related details: Needle clip adjustment upwards: When the needle clip is adjusted upwards, the needle position moves relatively downward, and the annular main nozzle of the carburetor also decreases. At this time, the combustible air-fuel mixture delivered to the cylinder head through the main nozzle becomes leaner. Conversely, a richer combustible air-fuel mixture is obtained. Needle position adjustment: Adjusting the needle position will directly cause a noticeable change in the carburetor's air-fuel mixture ratio. Although it may start smoothly at different settings, under normal driving conditions, it can lead to various engine issues, such as stalling when accelerating, incomplete combustion in the cylinder head, black smoke from the exhaust pipe, and a series of other problems.