4-Stroke vs. 2-Stroke

If you are looking at a smaller scooter, you may need to choose between a 2-stroke and a 4-stroke engine. But what’s the difference, and which one should you get?

The names refer to how many strokes of a piston it takes to accomplish the 4 processes of a combustion engine: intake, compression, combustion, and exhaust. Up and down counts as 2 strokes. The primary difference is that a 4-stroke mixes oil into the engine from a reservoir separate from the gasoline (like your car); while a 2-stroke wants its oil mixed in with the gas (like an old lawn mower). A 4-stroke has to go around again, without firing the spark plug, to draw in the oil and lubricate the cylinder. The 2-stroke, its oil mixed with the fuel, burns that oil. You can smell it and see it in the blue smoke. If you have heard people talk about scooters being bad for the environment… or even the myth that they are worse than SUV’s… those people are talking about 2-strokes. If going green is your thing, get a 4-stroke.

So why a 2-stroke? Well, in a way, it is a more efficient engine. There isn’t that part of the piston’s stroke that is lubricating the cylinder. Therefore, more energy is put directly to drive. A 2-stroke is going to be faster than a 4-stroke of the same size. 2-strokes are simpler and easier to hop-up. If performance is your thing, and you plan to work on it yourself, you are going to get more out of a 2-stroke. But you may need to buy used, as environmental laws have most makers switching to 4-strokes. An exception is the 2008 Zuma by Yamaha.