1. Piston-controlled ports: This system is the most common and cost-effective in two-cycle engines. The ports are incorporated into the cylinder walls and are covered and uncovered by the piston's movement during its upward and downward strokes. These ports are responsible for controlling the timing and duration of the intake, transfer, and exhaust processes in the engine.
2. Rotary disc valve: In this system, a circular disc with openings is rotated by a gear or chain mechanism to control the opening and closing of intake and exhaust ports. The position and timing of the disc precisely synchronize with the piston's movement, allowing for efficient gas exchange.
3. Reed valve: Reed valves are thin, flexible flaps mounted at the entrance of intake or exhaust ports. They open and close due to pressure differences created by the piston's movement, facilitating proper gas flow into and out of the cylinder. Reed valves are often found in smaller two-cycle engines, such as handheld power tools and gasoline-powered model aircraft.
