THE 2-STROKE CYCLE A LOOK AT THE DEVELOPMENT OF THE 2-STROKE ENGINE
We all know what a 2-cycle engine is, right? It’s that little buzzy-sounding engine powering your weed eater or chain saw! They have been around as long as we can remember, and we don’t give them much thought. Just mix some oil into the gas and they do the job. We take for granted that they are called 2-cycle, because actually, the term should be “2-stroke cycle,” meaning there are two strokes of the piston, one up and one down, to complete a power cycle, with power created on every revolution of the crankshaft. The diagram in Photo 1 shows this quite well.
One might ask then, what is the 4-cycle engine? Again, the correct term should be “4-stroke cycle,” as there are four strokes of the piston to complete one power cycle. First, the piston goes down on the intake stroke, then it pushes back up on the compression stroke, then it’s pushed down again on the power stroke, and finally it goes back shows this nicely. Note that the 4-cycle engine has only one power stroke for every two revolutions of the crankshaft versus the 2-cycle engine’s power stroke for every revolution of the crankshaft.
