What is the function of the carburetor needle height adjustment?
1 Answers
It forms an annular main nozzle with the carburetor's main jet to deliver a certain amount of combustible air-fuel mixture to the cylinder head. Below are the relevant explanations: 1. When the needle clip is adjusted upward, the needle position moves relatively downward, reducing the annular main nozzle of the carburetor. This results in a leaner combustible air-fuel mixture delivered to the cylinder head through the main nozzle, and vice versa for a richer mixture. 2. Adjusting the needle position directly causes noticeable changes in the carburetor's air-fuel ratio. Although the engine may start smoothly under various settings, it can lead to different engine faults during normal operation, such as stalling when accelerating, incomplete combustion in the cylinder head, black smoke from the exhaust pipe, and a series of other issues.