Two-stroke power valve system

The 2-stroke power valve system is an improvement to a conventional two-stroke engine that gives a high power output over a wider RPM range. 2-stroke power valve system.

Two stroke engines use a Power valve.

Operation of a 2-stroke engine

A stroke is the action of a piston traveling the full length of its cylinder. In a two-stroke power valve system, one of the two strokes combines the intake and the compression stroke, while the other stroke combines the combustion and exhaust stroke.

As the piston travels upward in the cylinder, it creates a vacuum in the crankcase; this draws fresh air and atomized fuel from the carburetor through a hole in the cylinder wall. As the piston continues travelling upward, transfer ports that are responsible for delivering the fresh air-fuel mixture to the cylinder are closed off, thus trapping the combustible mixture. As the piston reaches the top of the cylinder, the mixture in the cylinder is compressed to the point of ignition.

The second stroke begins once ignition has taken place. The combustion-or power-stroke begins as the air-fuel mixture is ignited. The burning fuel creates pressure in the cylinder above the piston and forces it downward. As the piston passes the midpoint of the downstroke, the exhaust port to the side of the cylinder starts to open and initiates the flow of burned fuel out into the expansion chamber or muffler through the manifold.

As the piston is forced downward, positive pressure builds up in the crankcase where the air-fuel mixture remains from the previous intake-compression stroke. Shortly after the exhaust port is uncovered by the downward travel of the piston, the transfer ports begin to be uncovered. The transfer ports act as a passage through which the air-fuel mixture moves from the crankcase into the cylinder above the piston. The rush of the fresh air-fuel mixture as it enters the cylinder helps to push out residual exhaust gases. Once the piston reaches the bottom of the stroke, the second cycle is completed and the process is repeated.