Chief Gunner
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Baby Hog, I've included a little info on 2 stroke vs. 4 stroke. I appologize if you already understand the difference. I think what Earlytimes was getting at is that modifying a 4 stokes breathing ability can have noticible gains while a 2 stroke not so much. So when Bill mentioned the 2 stroke motor ......... a 2 cycle fires every stroke, a 4 cylinder every other stroke. Sooo a 2 cycle fires more per RPM than a 4 cycle engine.
How They Work There is a marked difference in how a 2-cycle and 4-cycle motor operates. A 4-cycle engine works, as you might expect, in four stages. There is the power (down) stroke, the exhaust (up) stroke, the intake (down again) stroke, and the compression (up again) stroke. It takes two full revolutions of the crankshaft to deliver these four strokes. It's the power stroke which sends the piston through each of the three remaining stages.
A 2-cycle engine literally has just two cycles that combine the above duties. The first stroke is the combination power and exhaust stroke and the second combines the compression and intake stroke. Both power and combustion happen as the piston reaches to top of its stroke. At the bottom, the exhaust and intake occur. It takes just a single revolution to generate two strokes and propel the piston through its full cycle.
More Parts = More to Break Four-cycle engines have a lot more moving parts. They have a crankshaft, camshaft, connecting rod, valves, lifters and of course the piston. A two-cycle engine really has only three major moving parts. This includes the crankshaft, connecting rod and the piston. In small size two cycle engines there are no cams, lifters or valves. As a general rule, less parts equals less potential for failure and easier maintenance. Overall, the 2-cycle engine is typically smaller in displacement and size as compared a 4-cycle which, many times, is almost double the displacement and overall size to achieve the same power. The reason for this is because since the 2-cycle combines two functions in one rotation, it makes the power twice as quickly as a 4-stroke.
The fact is, 4-cycle only has a few advantages: greater potential torque, higher fuel economy, and better emissions.
Greater Potential Torque = The reason we are playing with it
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