What is the name of the round disc in a carburetor located beyond the main fuel nozzle?

The correct term for the round disc in a carburetor located beyond the main fuel nozzle is the throttle. The throttle is a critical component in regulating the air-fuel mixture entering the engine, as it controls the engine's power output and speed. When the throttle valve opens, it allows more air to flow into the engine, which in turn increases the amount of fuel drawn from the main fuel nozzle, leading to higher engine performance.

The choke, while an important part of the carburetor, is mainly used to restrict airflow during cold starts to enrich the fuel mixture. The float is involved in maintaining the proper fuel level in the carburetor bowl, while the needle valve controls the flow of fuel into the carburetor but is not a disc. Understanding the function of the throttle is essential for recognizing how carburetors work and how they influence engine performance.