The Two-stroke Cycle
The following animation shows a two-stroke engine in action. You can compare this animation to the animations in the car engine and diesel engine articles to see the differences. The biggest difference to notice when comparing figures is that the spark-plug fires once every revolution in a two-stroke engine.
This figure shows a typical cross flow design. You can see that two-stroke engines are ingenious little devices that overlap operations in order to reduce the part count.