How Things Work How-4-stroke-engines-work

Published on September 9th, 2015 | by Kimberly Myers


How 4 Stroke Engines Work

What is a 4 Stroke Engine?

A 4-Stroke engine is the kind of engine that you usually see in lawn mowers and cars. It is heavy and has to remain in an upright position to be used, so it doesn’t work so well on lawn equipment such as weed eaters and chainsaws. They are more expensive than 2 stroke engines due to the complexity of the engine and the repairs that would be necessary to fix them if something were to go wrong.

Main Components:

  • Intake Valve
  • Exhaust Valve
  • Valve Cover
  • Intake Port
  • Cylinder Head
  • Spark Plug
  • Piston
  • Connecting Rod
  • Crankshaft


How it Works:

  • The engine is fired up, either by electric, or a recoil start
  • The piston moves up and compresses a fuel and air mixture in the chamber (compression stroke)
  • Fuel is ignited by the spark plug and it drives the piston down providing the necessary   momentum to keep the crankshaft turning (power stroke)
  • The piston moves back up and pushes the used/burned gasses out of the exhaust valve ( exhaust stroke)
  • The piston goes back down and draws the fresh air and fuel in preparation to move back up and compress the air (intake stroke)
  • This process keeps the engine running

Maintenance Tips:

Featured Parts:

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