A “small” engine typically refers to an engine that produces less than 25 hp (horsepower). Small engines can be used for various applications and are often found in outdoor equipment such as lawnmowers, tractors, generators and more. They consist of several different systems that work together to generate power, with many parts that make up each system.

What Are the Basic Parts of a Small Engine?

When it comes to small engine parts and what they do, there is some essential information to keep in mind. Below is a breakdown of the main small engine parts and terms associated with each system of the engine.

Fuel and Exhaust

  • Carburetor: The device that automatically mixes fuel in correct proportion with air to produce a combustible gas.
  • Fuel line: The line through which fuel from the tank is moved to the carburetor.
  • Throttle: Controls the amount of air-fuel mixture that enters the engine from the carburetor.
  • Muffler: Reduces the noise made by the passage of exhaust gases.


  • Spark plug: An isolated electrode that is attached to the top of the engine cylinder and helps to produce the spark needed to power the engine.
  • Battery: Stores electrical energy until it is needed to power the equipment.


  • Piston: A cylindrical part that compresses the air-fuel mixture when moved upward.
  • Crankshaft: Works in conjunction with the connecting rod to move the piston.
  • Connecting rod: The rod that connects the piston and the crankshaft.
  • Valves: Open and close passages for fuel and air.

Lubrication and Cooling

  • Oil filter: Removes contaminants from circulating in the oil.
  • Bearings: Movable parts used to reduce friction created during the combustion process.
  • Fans: Most small engines are cooled by air using fans that are situated around the outside of the combustion chamber.

Contact Prime Source Parts and Equipment for Your Small Engine Parts

At Prime Source Parts and Equipment, we use our vast network of suppliers to help our customers find the parts they need. We also have experienced technicians to provide you with invaluable support services. Contact us today to find out more about our small engine parts and services.