Picture of How To Tune Up a Two Cycle Engine
All two-cycle engine tune-ups involve the same parts: spark plugs, air filters, and fuel filters. This article explains the basics of a two-cycle engine tune-up.

Small engines are used in all kinds of power tools and lawn & garden equipment, and like all engines, 2-cycle engines should get a tune-up at least once a year.

The most common mistake that small engine owners make about tune-ups is waiting for the engine to stop working before doing one.

Tune-ups are intended to keep an engine running, not to fix it once it stops. If your engine has stopped working, its possible that the problem could have been prevented with regular tune-ups.

This article explains the steps for a simple 2-cycle engine tune up, including air filter, spark plug, and fuel filter replacement. We use a Shindaiwa T242 Trimmer as a demonstration model for this tune-up, but these steps apply to all 2-cycle engines. 

You will need the following items for this tune-up:

  • a ratcheting socket wrench
  • a new air filter
  • a new spark plug
  • a new fuel filter
  • a hooked wire
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Step 1: Replace the Air Filter

Picture of Replace the Air Filter
Air filter housings are located in different places on different engines, but they're usually in an accessible area on the outside of the block. In the case of this Shindaiwa trimmer, the air filter housing is located on the side of the engine.

Your engine's air filter will be visibly dirty when it's ready for a replacement, and like other tune-up maintenance items, it should be replaced at least annually.

To replace the filter, simply remove the air filter housing, take the old air filter out, install the new filter, and then close the housing.

Most air filter housings open and close with a simple screw.
jim.rosent6 months ago
When my Weed Whacker wouldn't start I started checking different things. I changed the plug. It'd start briefly if I primed it, but I realized something else was wrong. I found the fuel line broken in pieces. There are 2 lines coming out of the tank. The top one goes to the priming bubble & the other's below that & goes into the engine. Which one is the fuel filter supposed to go on? How do I replace the line(s)?