Considerations for that Stubborn Two-Stroke Engine

Finiky 2-stroke weed-eater

_by David Hilgendorf |Fall, 2024

Few things are more annoying than trying to start a gas-powered two-stroke engine when there’s work to do. Fortunately, two-stroke engines are pretty simple, so most DIYers with a few tools and some basic knowledge can perform the necessary troubleshooting to get their tools and equipment running again.

Top 10 Two-Stroke Applications

  1. Chainsaws: Tree felling, forestry and firewood enthusiasts
  2. Pole Saws: Overgrowth tree limb trimmer.
  3. Leaf Blowers: scattering around leaves and debris. Annoying!
  4. String Trimmers: Weed-Eaters for grass, weeds and small plant landscaping.
  5. Hedge Trimmers: Hedge and shrub shaping and maintenance.
  6. Brush Cutters: Manage dense vegetation.
  7. Garden Tiller: Soil preparation.
  8. Water Transfer Pump: Irrigation and drainage. I love mine!
  9. Outboard Marine Motors: Small boat and watercraft propulsion. Still the way to go!
  10. Dirt Bikes: Light and responsive off-road motorcycles.
  11. One more!! Lawn Mowers – Two stroke mowers are still the way to go if you can find one!

Internal-combustion engines require a steady supply of air and fuel to run properly and produce maximum power. Two-stroke oils with poor detergency properties can allow varnish and carbon deposits to build up in various places, which chokes off air and fuel delivery, causing the engine to lose power, run poorly, start hard and eventually fail to start at all.

Troubleshooting

1) Bad Gasoline

Gasoline can break down in as little as 30 days, especially if it contains ethanol. Storing your equipment in the garage over the winter without stabilizing the gas is a recipe for equipment that won’t start in the spring. Varnish and gum which is created over time can also plug the fuel filter and restrict flow. Attend to those full gas tanks before you store it away for any length over 3 months.

Solution: Clean or replace the fuel filter, drain the tank and refill with fresh fuel.

2) Dirty Carburetor and carboned up engine – likely in 2-strokes

You NEED Power Foam!

Once gas breaks down, varnish, gums and other debris can form inside the carburetor and clog the tiny fuel passages preventing fuel from reaching the combustion chamber.

Solution: Clean the carburetor and upper cylinder area by spraying AMSOIL Power Foam into the intake and letting it sit for several minutes to help dissolve the varnish. If it still won’t start, remove the carburetor and spray AMSOIL Power Foam directly into all openings, then reassemble.

3) No Spark

Oil, flooding and carbon deposits can foul the spark plug preventing it from firing.

Solution: Clean the deposits from the electrode with a wire brush or light-duty sandpaper or replace the spark plug.

4) Dirty Air Filter

A clogged air filter prevents the engine from receiving the oxygen needed for combustion. Tap rigid filters on a hard surface or blow compressed air from inside out to dislodge any dirt or debris.

Solution: Wash foam filters with mild detergent and replace paper filters.

5) Clogged Spark Arrestor

A small screen may cover the exhaust outlet to prevent sparks from exiting. This screen can become plugged with carbon deposits when using low-quality two-stroke oil, which leads to power loss.

Solution: Remove the spark-arrestor screen and spray it with AMSOIL Power Foam to soften the deposits before cleaning. Replace the screen if it’s clogged after cleaning.

Prevention: The Most Advanced Two-Stroke Oil

Low-quality two-stroke oil creates heavy carbon deposits and is the cause of many problems with two-stroke equipment not starting. Using a high-quality non-OEM two-stroke oil that burns cleanly and helps prevent carbon deposits is one of the easiest maintenance practices to ensure your two-stroke engines start easily, run efficiently and last for many years.

AMSOIL SABER® Professional 100% Synthetic 2-Stroke Oil withstands high-temperature operation to fight carbon buildup in gas-powered two-stroke engines. Its excellent detergency properties fight power-robbing deposits to keep exhaust ports and spark arrestor screens clean for easy starting and maximum power.

In independent testing, AMSOIL SABER Professional mixed at 100:1 provided better performance and fewer carbon deposits than a leading competitor’s two-stroke oil mixed at 50:1, offering the convenience of one mix ratio for all your two-stroke equipment. Plus, it’s formulated with gasoline stabilizer to help keep fuel fresh during short-term storage.

You can save time and money and gain the peace of mind that your two-stroke equipment will start and run optimally all year long simply by switching to AMSOIL SABER Professional.

What I like best about Saber Pro is the ease of mixing. We recommend 100:1 in EVERYTHING But I have found in certain bottle sizes like the 8-ounce mixes so easily at 80:1 which works in everything as well.  8 ounces for 5 gallons.

 

If all else fails in your 2-cycle engine problems, you can find on Ebay just about every carburetor for modern 2-cycle equipment. Sometimes the carb is beyond repair, and they can be a royal pain to adjust. I’ve found one for my blower for under $30 and made it run and idle like new!

 

Fix 2-Cycle Engine Problems
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