How two stroke engines work

For most people, engines are a mystery. Here's an excellent explanation and animation of how a 2 cycle engine works.

The piston works as a compressor, intake valve and exhaust valve. On each stroke the piston compresses the air and gas mixture until combustion. Then, on the way down it uncovers an exhaust valve where the exhaust quickly rushes out. Immediately after, the piston uncovers a second valve, this time letting in a new batch of air and gas.

Because the piston is acting as each of these elements, not only is the engine light, but can operate in any orientation making it perfect for hand-held outdoor power equipment.