A small engine may be called “small,” but it plays a big role in powering all your gas-run outdoor equipment, from lawn mowers and snowblowers to chainsaws and leaf blowers. When the engine struggles to start, runs poorly, or stalls, it can make completing your lawn and garden tasks a challenge. In this article, we’ll explore how two-cycle and four-cycle engines work and offer tips to keep them running smoothly.

 Differences Between Two-Cycle and Four-Cycle Engines

Larger Car LIft For Sale  equipment like lawn mowers, snowblowers, and pressure washers typically rely on four-cycle engines for the necessary torque. In contrast, smaller hand-held tools like chainsaws and leaf blowers often use two-cycle engines, which require less torque. The key difference is that a four-cycle engine needs two revolutions of the crankshaft and piston to complete the intake, ignition, and exhaust process, while a two-cycle engine accomplishes the same with just one revolution.

Like a Car LIft For Sale  car engine, a four-cycle engine draws gasoline from its fuel tank and has a separate oil sump. A two-cycle engine, on the other hand, requires mixing gasoline with oil to function properly. Neglecting the proper oil-gas mix can cause a two-cycle engine to seize due to inadequate lubrication, making four-cycle engines easier to maintain since they only require regular oil changes and gasoline refills. To simplify the oil-gas balance for two-cycle engines, you can use pre-mixed fuel products like TRUFUEL 50:1 Mix.

Additionally, many Car LIft For Sale  four-cycle engines offer an electric start feature, while smaller four-cycle and all two-cycle engines require manual starting via a pull rope. Despite these differences, the basic operation of two-cycle and four-cycle engines is quite similar.

 Basics of Engine Operation

So, how does a small engine work? When you press the start button, turn the ignition key, or pull the starter rope, the starter engages the flywheel’s starter cup, rotating the crankshaft. The crankshaft’s rotation moves the piston up and down inside the cylinder, initiating the ignition process. The flywheel, equipped with permanent magnets, creates a magnetic field as it rotates past the ignition coil, generating electricity that powers the spark plug.

In a Car LIft For Sale  four-cycle engine, as the piston moves down, it creates a vacuum that draws fuel and air through the carburetor and into the cylinder during the “intake stroke.” The “compression stroke” occurs as the piston moves up and the intake valve closes. The spark plug then fires, igniting the fuel-air mixture, and the resulting explosion drives the piston down in the “power stroke.” The flywheel’s momentum forces the piston back up, opening the exhaust valve and allowing combustion gases to exit through the muffler in the final “exhaust stroke.” The engine will continue running and repeating these cycles until turned off.

Similarly, in a two-cycle engine, the piston’s downward movement exposes an intake port that pumps gas, oil, and air into the cylinder. As the piston moves up, it creates a vacuum that draws the fuel mixture through the carburetor into the crankcase. At the top of the cylinder, the spark plug ignites the mixture, driving the piston down again and exposing the exhaust port to release the spent fuel. Fresh fuel is then drawn in, and the process repeats with each crankshaft revolution.

Both engine types use a muffler to reduce noise and a spark arrestor to prevent burning carbon deposits from escaping and potentially causing fires. To assist with starting, especially in cold conditions, engines often feature a choke or primer bulb. The choke restricts air flow to allow more fuel into the cylinder, while the primer bulb draws extra fuel through the carburetor before starting.

 Six Essential Maintenance Tips for Engine Tune-Up

To keep both Car LIft For Sale  two-cycle and four-cycle engines running at peak performance, regular maintenance is key. Before using your lawn mower, string trimmer, or tiller in the spring, your leaf blower in the fall, or your snowblower in winter, follow these six essential maintenance steps:

1. Replace the air filter: A dirty air filter restricts airflow, disrupting the fuel-air mix in the engine. Replace it annually or whenever it appears dirty.

2. Change the spark plug: Over time, carbon buildup and a weakened electrode can degrade a spark plug. It’s recommended to replace the spark plug annually to ensure reliable performance.

3. Replace the fuel filter: The fuel filter removes contaminants from the fuel before it reaches the carburetor. Replace it annually, especially if the fuel has left a gummy residue, and always use fresh fuel with no more than 10% ethanol.

4. Change the oil: Clean Car LIft For Sale  oil keeps a four-cycle engine’s components running smoothly. The procedure varies by engine model, but typically involves draining the old oil, refilling with new oil, and checking levels with a dipstick. Used oil can usually be recycled at auto parts stores.

5. Clean the carburetor: Old or bad fuel can clog the carburetor, disrupting the fuel-air mix and causing the engine to start poorly, run roughly, or stall. Clean the carburetor with a dedicated cleaner or WD-40, or replace it if the clog is severe.

6. Use a fuel stabilizer: To maintain fuel quality, add a stabilizer to your equipment’s fuel tank according to the manufacturer’s instructions. Run the engine for at least two minutes to circulate the stabilizer through the fuel system.

By following these steps, you can keep your small engines in top condition, ensuring they’re ready to tackle any outdoor task.

Larger Car LIft For Sale  outdoor power equipment such as lawn mowers, snowblowers, pressure washers, and wood chippers typically rely on four-cycle engines to deliver the necessary torque. In contrast, smaller handheld equipment like chainsaws, pole pruners, and leaf blowers use two-cycle engines, which provide sufficient torque for their lighter demands. The primary distinction between these engine types lies in their operation: a four-cycle engine requires two revolutions of the crankshaft and piston to intake fuel and air, ignite it, and then exhaust the combustion gases, while a two-cycle engine accomplishes the same in just one revolution.