Answer: D - 1
B - 2
A - 3
C - 4
Step-by-step explanation:
The four-stroke cycle in Engine Operation is a series of processes beginning with the intake of air and fuel into valves, compression, combustion and subsequent release of gases to the atmosphere. The process begins with;
1. Intake Stroke - A mixture of air and fuel is drawn into the cylinder when the intake valves open. The downward movement of the piston causes the air and fuel mixture to be drawn into the cylinder.
2. Compression Stroke - The piston rises and compresses the fuel mixture in the combustion chamber near the spark plug. It occurs in a closed space. Ignition is made easy by causing energy release.
3. Power or Combustion Stroke - The fuel mixture is ignited by the spark plug and the resulting explosion caused by the mixture of air and fuel with oxygen, forces the piston down the cylinder.
4. Exhaust Stroke - The exhaust gases leftover from the combustion are released from the cylinder. This last stage is characterized by the opening of the exhaust valves and an upward push of the exhaust gases by the returning piston to the surrounding. The intake valve is closed at this stage.