How to Perform a Small Engine Tune-Up

Small, gasoline engines range from the very small, under 2 horsepower (usually found in weed trimmers and leaf blowers), up to larger multiple cylinder engines. The largest small engines, up to four cylinders and 30 or more horsepower require more involved tune-ups, specialized tools, and mechanical experience. However, the majority of small engines can be serviced by the homeowner with basic hand tools. A small engine tune-up is easy to do, requires few specialized tools, and can be completed quickly.

Difficulty: Moderate

Instructions

Things You'll Need:

• Screwdrivers - phillips & flat
• Small socket set
• Small open end wrench set
• Automotive filter wrench
• Spark plug gapping tool
• Pan for old oil & gas
• Rags for clean-up
• Clean, fresh gas
• Clean, fresh oil
• New, appropriate spark plug or plugs
• New, appropriate air filter
• New, appropriate fuel filter (if equipped)
• New, appropriate oil filter (if equipped)
• Engine manufacturer, model number, size, and serial number (for parts reference)

1. Determine whether you have a 2 or 4 cycle engine. 2 cycle engines require that you mix the gasoline with oil, are smaller and less powerful, but do run at higher speeds than 4 cycle engines. 4 cycle engines have separate oil and gasoline reservoirs, are generally larger and more powerful, and run at slower speeds.

2. 4 cycle engines will require that you replace the spark plug or plugs, air filter, fuel filter (if equipped), and change the oil and oil filter (if equipped). Additionally you may want to empty and clean the fuel tank and lines. 2 cycle engines only require replacement of the spark plug(s), air and fuel filters, as well as the optional fuel system cleaning.

3. Locate and remove the spark plug(s), using the appropriately-sized open end wrench, or ratchet and socket. Replace with the manufacturer's recommended spark plug. Be sure to set the plug to the correct gap size, using a spark plug gapping tool, following the engine manufacturer's recommendations. Tighten the plug until it contacts the cylinder head, and is tight.

4. Locate the air filter cover and remove, using a screwdriver, open end wrench, or ratchet and socket, depending on the cover's hardware. Remove any dirt and debris from the cover and filter holder using a clean rag. Replace the air filter with a new one, matching the manufacturer's recommendations.

5. If the fuel is old, or the engine hasn't been used for some time, drain the fuel tank and lines of all fuel. Flush the tank and fuel lines with a small volume of new, clean gas. Most small engines do not have a fuel filter. However, if equipped, locate and remove the fuel filter. Usually this will be located in between the fuel tank and carburetor, or on some models, attached directly to the tank or carburetor.

6. Changing the oil on small engines is an easy, though somewhat messy affair. Locate the oil drain plug and position a pan to catch the old oil. The plug will either be on the side of the engine near the base, or on the very bottom of the engine. Remove the plug and let the old oil continue to drain until the engine is empty. Some small engines have oil filters, most do not. If equipped, remove the old oil filter using a small automotive filter wrench. Lubricate the gasket of the new filter with clean oil before replacing. Be sure to use the appropriate new oil filter, following the manufacturer's recommendations. Tighten the new filter until the gasket contacts the mounting base, then three quarters to one more turn. Replace the oil drain plug and fill with the correct amount of manufacturer's recommended oil. Be sure not to overfill. Most small engines use 10W30 oil.

Tips & Warnings

• Small engines will benefit greatly from at least a yearly tune-up, or more often, depending upon the use they receive.
• If you have it, the engine owner's manual provides valuable information regarding all service, including the correct type of gas, spark plugs, filters, and oil.
• Finding the engine's name, model number, serial number, and size will help you locate parts.
• Your local hardware store, small engine repair shop, home improvement store, and the internet are all valuable resources.
• Be sure to properly dispose of old fuel and oil. Most oil change shops and automotive parts stores will accept used oil and fuel in sealed containers.
• Use caution when handling gasoline and oil.
• Make sure the engine is shut off and cool before performing any maintenance.
• Working on a large piece of old cardboard, scrap wood, or drop cloth will help minimize fluid spills or leaks.