Question

The choke in carburetor is provided to

• A. Cut off fuel supply
• B. Cut off air fuel mixture
• C. Control fuel mixture
• D. Control air supply

Hint:

Closing the choke restricts the air supply, creating a vacuum that draws extra fuel to deliver a rich air-fuel mixture for starting a cold engine.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
A carburetor is a mechanical device that mixes air and fuel in the proper ratio for combustion in an internal combustion engine.
To start a cold engine, a richer fuel-air mixture (higher fuel-to-air ratio) is required because fuel does not vaporize easily in a cold cylinder.
Detailed Explanation:
The choke is a butterfly valve located at the air intake entrance of the carburetor, upstream of the venturi.
When the operator engages the choke (closes the valve), it restricts or controls the incoming air supply to the carburetor barrel.
With the air intake restricted, a high vacuum is created inside the carburetor during the intake stroke.
This high vacuum draws more fuel through the main jet while reducing the volume of incoming air.
The resulting fuel-rich mixture is drawn into the cylinders, enabling the cold engine to start.
Once the engine warms up, the choke valve is opened to restore the normal air-fuel ratio.
Therefore, the choke valve is designed to control the air supply.

Step 2: Final Answer:
The choke in a carburetor is designed to control the air supply.