Battery-powered yard tools are taking over, but it’s not quite the end for gasoline-powered small engines. You can keep yours running smoothly for years with regular small engine maintenance and some inside knowledge. Dave Cheney of DC Carb shares several tips on small engine maintenance, including how to rebuild a carburetor, which is not as scary as it sounds. Learn about car tune-up basics, seasonal maintenance tips and lawn mower engine care, which help keep your machines running smoothly.

How to Keep Your Small Engines Healthy

Feed your machine fresh air

  • Small engines need clean air. A clean air filter allows maximum airflow and the optimum fuel/air mixture. You can and should clean the air filter.
  • If the air filter is too far gone or if it’s made of paper and it’s clogged, it needs to be replaced. This is a must-add to your seasonal maintenance tips list.

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Always use new gas

  • Small engines love fresh fuel. If your can of gasoline has been sitting around for more than four months, recycle that old gas.
  • Ethanol blends have an even shorter life. Through oxidation and evaporation, gasoline becomes less combustible. That leads to poor performance, rough idling and varnish deposits.
    Pro tip: Never add fuel stabilizer to old gas. It won’t bring gas back to life. You should only add stabilizer to fresh gas to extend its use.

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Avoid ethanol blends

  • Small engines prefer ethanol-free gas.
  • Ethanol attracts moisture from the air, which separates from the gas and sinks to the bottom of the tank. This can cause ignition problems.
  • Ethanol is also corrosive and burns hot, which can cause overheating and severe engine damage.

Check for spark

  • A spark plug checker can provide critical information.
  • First, it will tell you if electricity is getting to the spark plug.
  • Second, if there is no spark, it lets you determine the cause of failure. Don’t forget to go in for a spark plug cleaning.

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Inspect the Spark Plug

1. Clean and reuse

  • If the spark plug looks slightly brown and not too dark, gently clean the spark plug with a soft wire brush, check the gap and reinstall.

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2. Replace

  • Once your spark plug becomes an oil-fouled and deteriorated electrode, it needs to be replaced.
  • A new spark plug costs less than $10. It will create the right spark to best ignite the fuel/air mix in the combustion chamber.

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Is your carburetor too far gone? Buy a new one

If your carburetor has reached the point of no return, finding a new replacement online is easy. Cheney says Amazon and eBay are great places to start looking.

How to Rebuild the Carburetor

We’ve all done it—delayed fall maintenance until spring. The engine might fire up, but it won’t stay running for long. It’s time to disassemble and clean the carburetor.

1. Remove the carburetor

  • Disconnect the fuel line. If there’s still fuel in the tank, crimp the line to avoid leaks.
  • Most of the time, you’ll find two bolts holding the carburetor to the engine. Remove these bolts and the carburetor.

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2. Disassembly

  • After removing the main jet and the float bowl, Cheney pokes out the float hinge pin with a nail set.
  • Take the float off with care. The inlet needle and spring clip are under the float and are easy to lose.

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3. Remove the idle jet

  • A dirty idle jet is the reason small engines pulse and surge instead of idling smoothly. It’s also easy to overlook.
  • On this carburetor, the idle jet is behind a small plastic cap.
  • Cheney uses an old dental pick to pop out the cap. Then he removes the idle jet with a small flat-head screwdriver.

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4. Soak in carb cleaner

  • Soak the parts in Berryman Chem-Dip cleaner for 15 minutes. This takes care of most surface grime.
  • After soaking, use a brush to clean off any remaining debris.

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5. Deep cleaning

  • A deep clean removes debris not reachable by soaking.
  • Cheney uses an ultrasonic cleaner, but you can place parts in a pot of boiling water for 15 minutes.

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6. Clean the needle seat

  • To make sure the needle seats cleanly, clear debris out of the needle seat with a cotton swab.

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7. Reassemble and install

  • Lay the clean parts out on your bench and do one final inspection.
  • Reassemble the carburetor, bolt it to your machine and don’t forget to prime it.

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What Are the Rules for Seasonal Storage?

Drain the carburetor

  • You need to take one more important step after running your small engine out of fuel for the season.
  • Some gas will remain in the carburetor’s float bowl, so you need to drain it completely. Many carburetors have a small drain plug on the bottom of the float bowl for this purpose.
  • If left to sit, the gas will varnish and you’ll need to remove the carburetor to clean it.

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Don’t winterize—exercise

  • The easiest way to avoid the downside of seasonal maintenance tasks is to exercise your engine.
    Instead of draining the engine of all gas, keep the fuel tank full in the off-season and run the engine once a month for about 10 minutes. Cheney has used this technique for years. It saves him time and provides peace of mind.
  • He knows his small engines always have good gas and the internal workings are always coated in fresh oil.

Change the oil

  • Change the oil in your small engine every season.
  • Fresh, clean oil keeps sludge from building up and helps maintain good compression.
    Pro tip: Some lawn mowers don’t have an oil drain plug. The oil drains out of the fill tube at the top of the engine. Before you tip over your lawn mower to drain the oil, unscrew the gas cap and stretch a plastic over the gas tank opening. Then, screw the cap back on. The plastic will prevent gas from leaking out of the cap vent.

What Should You Have in Your Bench Kit?

Cheney depends on these tools the most in his shop for DIY engine maintenance.

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Screwdrivers

  • Basic? Yes. Indispensable? Yes.

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Flexible pry bar

  • This strong, non-marring poly/nylon pry bar won’t damage brass or aluminum. You can get a set for $10.

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Wrench

  • Cheney has a set of combination wrenches in imperial and metric.

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Needle-nose pliers

  • You’ll always need a pair when working on carburetors.

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Ratchet driver

  • This is a 1/4-in.-A driver with an extension that sockets into tight places.

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Dental pick

  • An old dental pick can poke, pull and clean where other tools can’t.

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Carb cleaner

  • Gumout carb cleaner is available at all auto parts stores.

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Slip joint pliers

  • These adjustable pliers are good to have on hand.

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Hose clamp pliers

  • Removal of flat-type or ring-type hose clamps is much easier with these ($14 online).

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Hose pinch

  • These locking pliers will clamp on a hose without causing damage ($25 online).

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Wire cutters

  • Cheney uses these for snipping linkages.

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Nitrile gloves

  • Cheney prefers these tough, black nitrile gloves.

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Wire brush

  • This is a must-have for cleaning small parts.

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Jet cleaning brushes

  • These micro-wire brushes remove debris from jets.

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FAQ

How often should I change the oil in my small engine?

When it comes to new small engines, you must change the oil after the first 5 hours. After that, you can change itevery 25-50 hours, butmake sure that you at least change it once per season. .
Pro tip: Always refer to your equipment’s manual. Oil change needs can differ for every piece of machinery.

Why won’t my small engine start after winter storage?

There can be a lot of possible reasons, including degraded fuel, dirty carburetor or spark plug, clogged filters, dead battery and moisture.

About The Expert:

  • Specializing in carburetor rebuilds, Dave Cheney, from DC Carb, has been wrenching on small engines for more than 30 years.

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