Here's why:
* Compression is essential for combustion: Just like 4-stroke engines, 2-stroke engines need compression to ignite the air-fuel mixture. Compression raises the temperature and pressure of the mixture, making it easier to ignite with a spark.
* Transfer ports: 2-stroke engines use transfer ports to direct the incoming fuel-air mixture into the combustion chamber. This happens *before* the piston reaches the top of its stroke, and is followed by compression as the piston continues upwards.
Why the confusion?
* No valves: 2-stroke engines don't use valves for intake and exhaust. Instead, they rely on ports in the cylinder wall that are uncovered and covered by the movement of the piston. This might lead some to think there's no compression because there's no separate valve for it.
* Pre-mixing: 2-stroke engines often use pre-mixed fuel, which can make the air-fuel mixture seem less dense.
In summary: 2-stroke engines have compression just like 4-stroke engines, but they achieve it through a different mechanism. It's essential for their operation, allowing them to ignite the fuel-air mixture and produce power.
