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Consumer Guide To Environmentally Helpful Outdoor Power Equipment

A Word About Gas-Powered 2-Cycle & 4-Cycle Engines

Throughout this guide, you will find references to four-cycle and two-cycle engines.

Two-cycle engines require the operator to pre-mix specially formulated two-cycle oil with unleaded gasoline before adding to the two-cycle equipment's fuel tank. With a four-cycle engine, the operator only needs to add unleaded gasoline to the fuel tank. Two-cycle oil is available from power equipment dealers and at the yard and garden sections of discount chains, home centers and hardware stores. Also remember that using a non-spill container to store fuel can be environmentally helpful.

Technical Differences Between 4-Cycle & 2-Cycle Engines

Four-cycle engines create power through the combustion of a controlled fuel/air mixture burned inside the combustion chamber of the engine. The combustion process is ignited by the spark plug.

The force of the rapidly burning/expanding fuel mixture drives the piston and connecting rod down the cylinder. This assembly is connected to the crankshaft that rotates either a mower blade, drive belt or transmission and axle for power and operating products.

A four-cycle engine also uses a separate oil reservoir like an automobile to lubricate moving parts.

Four-cycle engines are available with either a side valve design or overhead valve design. Compared to side valve designs, overhead valve engines run cooler and cleaner with more fuel efficiency. Low-emission side valve engines also tend to be lower in cost than overhead valve designs.

A two-cycle engine operates on the same spark plug/ignition principle as a four-cycle engine, except that it turns a mixture of two-cycle oil and gasoline in the same combustion chamber.