A 2-stroke engine is a type of small internal combustion engine that uses two different piston strokes to complete one operating cycle. During this cycle, the crankshaft rotates once while the piston goes up and down once to fire the spark plug.

2-Stroke Engine Parts List

The parts of a 2-stroke petrol engine include:

  • Fuel injector
  • Cylinder
  • Cylinder head
  • Spark plug
  • Crank
  • Crankshaft
  • Crankcase
  • Connecting rod
  • Ports — inlet, transfer and exhaust
  • Piston
  • Piston rings

Cycles of a 2-Stroke Engine

When it comes to the parts and function of a 2-stroke engine, there are two cycles.

1. First Stroke (Suction and Compression)

During this cycle, the piston moves from the bottom center to the top center, and all three ports — inlet, transfer and exhaust — are closed. The charge above the piston is compressed, and the spark plug ignites the charge and creates a power stroke. That power is transferred with the help of the connecting rod to the crankshaft.

There is also a partial vacuum created in the crankcase, which opens the inlet port and allows the fuel-air mixture inside.

2. Second Stroke (Power and Exhaust Stroke)

During the second cycle, the piston moves down from the top center, and the inlet port is closed. The downward motion of the piston pushes the fuel-air mixture, and the charge from the crankcase comes out through the transfer port.

Because the exhaust port is open, most of the exhaust gas leaves the cylinder. The exhaust gas that remains is pushed through the exhaust port by the pressure of the fuel-air mixture flowing downward. Then, with the help of a fresh charge, the exhaust gas is pushed out.

The parts of a 2-stroke petrol engine work this way, and the parts of a 2-stroke diesel engine work similarly except it has a fuel injector instead of a spark plug.

Contact Prime Source Parts and Equipment Today

Whether you need parts for a 2-stroke marine diesel engine or a 2-stroke petrol engine, Prime Source Parts and Equipment can help. Contact us today for more information about our small engine services.