 lubrication. In this instance, a four-cycle engine is the easier engine to maintain (just pour the gasoline into the tank as you would for your car and remember to change the oil regularly). If you’re concerned about getting that gas/oil balance right for your two-cycle engines, you can use a pre-mixed fuel and oil product like TRUFUEL 50:1 Mix to fill the tank.
Additionally, a larger four-cycle engine may utilize an electric start feature that allows the engine to be turned over by using an ignition key or a start button. Smaller four-cycle engines, and all two-cycle engines, rely on the operator to pull a starter rope to fire the engine up. Apart from these differences, the basics of two-cycle and four-cycle engine operation are quite similar.
So, how does a small engine work? When the start button is pressed, the ignition key turned, or the rope is pulled, the starter engages the starter cup on the flywheel and rotates the crankshaft. The rotating crankshaft connects to the piston which moves up-and-down within the cylinder and ignition process begins. The flywheel has permanent magnets built into it, and as it rotates past the ignition coil, a magnetic field is created. The magnetic field induces electricity, allowing the ignition coil to send voltage to the spark plug.
At the same time on a four-cycle engine, the piston will travel down the cylinder creating a vacuum that draws fuel and air through the carburetor where they mix before entering the cylinder through an intake port. This action is called the “intake stroke”. Next, the “compression stroke” takes place as the piston travels back up to the top of the cylinder and the intake valve closes. The spark plug now fires and ignites the fuel and air mixture which forces the piston down (known as the “power stroke”). The momentum of the spinning flywheel provides enough force to push the piston back up. The exhaust valve will then open, and the combustion gasses will exit through the muffler in what is the fourth and final cycle – the “exhaust stroke”. A four-cycle engine will continue to run and repeat these four cycles until it is turned off.
Similarly, as a two-cycle engine’s piston travels down the cylinder, it exposes an intake port and pumps gas, oil, and air into the cylinder. As the piston travels back up the cylinder, a vacuum is created and the gas, oil, and air is drawn through the carburetor into the crankcase. When the piston reaches the top of the cylinder, the energized spark plug will ignite the fuel and air mixture, driving the piston down, exposing an exhaust port where the spent fuel exits. A split-second later, the intake port is exposed again. Fresh fuel is drawn in and the process continues with every revolution of the crankshaft.
The exhaust from both two-cycle and four-cycle engines will travel through the muffler and, often, a spark arrestor. The muffler reduces engine noise while the spark arrestor prevents burning carbon deposits from exiting the engine and, potentially, starting a fire.
Engines will have a choke, primer bulb, or both to assist with starting, especially when the engine is cold. The choke will temporarily restrict air flow through the carburetor so more fuel can enter the cylinder. Likewise, a primer bulb draws additional fuel through the carburetor before the engine is started.
Install a new air filter – A dirty air filter inhibits good airflow, preventing the proper ratio of fuel and air from entering the engine cylinder. The air filter is easy to replace and should be done annually or whenever the filter appears soiled.
Change the spark plug – Due to carbon build-up and a weakened electrode, a spark plug will degrade over time. You can inspect the spark plug for damage and test the component using an ignition tester to determine whether it’s defective or not, but this is another part that should simply be replaced once a year.
Replace the fuel filter – The fuel filter helps to remove contaminants from the fuel before it leaves the tank and enters the carburetor. Old or bad fuel can leave a gummy residue in the filter, significantly weakening the fuel flow. For this reason, it’s a good idea to replace the filter annually as a preventative measure (and keep the fuel fresh, making sure it contains no more than 10% ethanol).
Change the oil – To keep a four-cycle engine’s crankshaft, piston, and gears working smoothly, you need clean oil. While the procedure for replacing the oil will differ depending on the engine model, you can usually unthread the oil tank cap, remove the dipstick, if applicable, and carefully tip the engine to empty the old oil into an approved container. Outdoor power equipment engine oil, like car engine oil, can be recycled at most auto parts stores. Once the oil tank is emptied, return the engine to its upright position, and pour the new oil into the oil fill tube. To avoid overfilling, pour in approximately three-quarters of the bottle, then check the tank with the dipstick to determine if the oil level is at full. You can then add more oil, as necessary.
Keep the carburetor clean – As with the fuel filter, old or bad fuel can leave a gummy residue inside the carburetor as well which can create a restriction. This will prevent the proper ratio of fuel and air from entering the cylinder which can cause the engine to have trouble starting, or may cause it to run rough, or stall. You can try cleaning the carburetor ports with a dedicated carburetor cleaner, or WD-40, to clear out the restriction, but if the clog is particularly bad, you may need to replace the carburetor with a new one.
Use a fuel stabilizer – While you should only use fresh fuel when filling your outdoor power equipment’s fuel tank, you can use a fuel stabilizer to help maintain the quality of that fuel. The stabilizer can be added to a fuel can or the equipment’s fuel tank, but you should refer to the manufacturer’s instructions to determine the proper amount for both. If adding the stabilizer to the equipment’s fuel tank, be sure to run the engine for at least two minutes to circulate the stabilizer throughout the fuel system.
Whether you’re looking to repair your small engine or just keep it tuned-up, Repair Clinic makes it easy to find the parts you need. Just type the full model number of the engine in the Repair Clinic website search bar to identify the specific parts associated with the engine, from the right spark plug and air filter to the compatible carburetor, fuel filter, ignition coil, flywheel, and recoil starter. Repair Clinic stocks genuine manufacturer parts for all the big names in small engines, such as Briggs & Stratton, Craftsman, Honda, Husqvarna, Kawasaki, Kohler, MTD, Snapper, Tecumseh, Toro, Walbro, and Zama, but you’ll want to make sure you’re purchasing the exact item that matches your engine model.Kenneth J. Saltman is professor of educational policy studies and research at DePaul University in Chicago. He is the author most recently of Failure of Corporate School Reform (Paradigm Publishers 2012), The Gift of Education: Public Education and Venture Philanthropy (Palgrave Macmillan 2010) and Capitalizing on Disaster: Taking and Breaking Public Schools (Paradigm Publishers 2007). His edited collection, Education as Enforcement: the Militarization and Corporatization of Schools, Second Edition has just been released (Routledge 2010).
The authors of “Toward a New Common School Movement” argue for defending a not-yet-realized “public” in public schools.
Faced with an improbability of forcing the 230kv Dufferin Wind Power (DWPI) transmission line to be buried wherever it crosses the township, Amaranth council has asked both Premier Kathleen Wynne and Prime Minister Stephen Harper to have work on the wind farm stopped.
A township council motion of Feb. 19 by Deputy Mayor Walter Kolodziechuk gives five reasons why the council considers the transmission line and the wind farm should be considered prematurely approved, and asks for “an immediate moratorium on this project until ordinary people are assured, given the proof, of their safety and security and the environment that surrounds them.
“And further that health studies be undertaken immediately to establish a baseline before operation of the Wind Farm and Transmission Line and that a compensation plan be in place to protect people, their health and wealth,” the motion reads.
The appeal was directed personally to the premier and the prime minister.
Not surprisingly, the first of the five reasons cited was related to the transmission line.“Whereas the Ontario Energy Board has approved the (DWPI) project, specifically ignoring human health and environmental impacts…,” the reason states before moving on to cite opposition from the affected municipalities, among other things mainly health-related.
The apparent emphasis on the power line is not surprising, as both Amaranth and Melancthon have stated in the past that they feel like second-class municipalities since the line would be buried through more densely populated Shelburne.
If there is no risk to human health from overhead high voltage lines, they have asked rhetorically, why bury the line through an urban area and past a school.
As well, Amaranth Mayor Don MacIver had appeared as a presenter at the Environmental Review Tribunal to speak passionately against upholding the OEB’s leave to construct the line in accordance with the design. He pointed out, in addition to health effects he had researched, that Amaranth’s rules are that such power lines must be buried