Basic Small Engine Theory Pretest

What is the primary function of the intake stroke in a 4-stroke engine?

• To expel exhaust gases

• To draw air-fuel mixture into the cylinder

• To compress the air-fuel mixture

• To ignite the air-fuel mixture

Which component in an ignition system is responsible for generating the high voltage needed to ignite the air-fuel mixture?

• Spark plug

• Distributor

• Ignition coil

• Battery

Explain how a governor system maintains the speed of an engine.

• By adjusting the fuel-air mixture

• By controlling the ignition timing

• By regulating the throttle position

• By altering the compression ratio

• 8:1

• 9:1

• 10:1

• 11:1

Describe the role of the venturi effect in a carburetor's operation.

• It increases the air pressure to atomize the fuel

• It decreases the air pressure to draw fuel into the airstream

• It stabilizes the air-fuel mixture

• It controls the engine speed

Analyze the impact of advancing the ignition timing on engine performance and emissions.

• Increases power and reduces emissions

• Decreases power and increases emissions

• Increases power but may increase emissions

• Decreases power but reduces emissions

Evaluate the effectiveness of a mechanical governor versus an electronic governor in terms of response time and accuracy.

• Mechanical governors are faster and more accurate

• Electronic governors are slower but more accurate

• Mechanical governors are slower and less accurate

• Electronic governors are faster and more accurate

What is the effect of a higher compression ratio on the thermal efficiency of an engine?

• Decreases thermal efficiency

• Increases thermal efficiency

• Has no effect on thermal efficiency

• Reduces engine power

Identify the main advantage of using a multi-barrel carburetor over a single-barrel carburetor.

• Simplicity in design

• Improved fuel economy

• Better air-fuel mixture distribution

• Easier maintenance

Discuss the potential consequences of incorrect ignition timing on engine operation.

• Increased fuel efficiency and reduced emissions

• Engine knocking and reduced performance

• Smooth engine operation and increased power

• Lower engine temperature and increased lifespan