EETC - Equipment & Engine Training Council Two-Stroke Engine Principles Questions and Answers

Question 1

In a piston-ported two-stroke engine, what two events occur simultaneously as the piston moves from Bottom Dead Center (BDC) to Top Dead Center (TDC)?

Accepted Answer

Intake (into crankcase) and compression

Answer

Power and exhaust

Answer

Scavenging and intake (into cylinder)

Answer

Exhaust and intake (into crankcase)

Question 2

A customer complains their chainsaw, a two-stroke engine, is producing excessive blue smoke and has a fouled spark plug. Which of the following is the most likely cause?

Accepted Answer

An incorrect fuel-to-oil ratio (too much oil)

Answer

A clogged air filter causing a lean mixture

Answer

Worn piston rings causing oil to leak from a sump

Answer

A malfunctioning ignition coil

Question 3

Which of the following describes the primary function of reed valves in a two-stroke engine?

Accepted Answer

To act as a one-way check valve for the intake tract, preventing blowback.

Answer

To regulate the timing of the exhaust port opening.

Answer

To control the flow of coolant through the engine.

Answer

To mix the oil and fuel automatically before they enter the crankcase.

Question 4

The process of using the incoming fresh air-fuel charge to push the burnt exhaust gases out of the cylinder is known as:

Accepted Answer

Scavenging

Answer

Porting

Answer

Pressurization

Answer

Combustion

Question 5

Which type of scavenging directs the incoming charge upward in a looping path to force exhaust gases out, with both transfer and exhaust ports located on the same side of the cylinder?

Accepted Answer

Loop scavenging

Answer

Cross-flow scavenging

Answer

Uniflow scavenging

Answer

Piston-port scavenging

Question 6

In a typical two-stroke engine's port timing sequence, which port is the first to open as the piston moves downward on the power stroke?

Accepted Answer

The exhaust port

Answer

The intake port

Answer

The transfer port

Answer

The boost port