An exemplary two-stroke internal combustion engine can comprise one or more cylinders comprising exhaust ports, one or more pistons configured to cyclically cover and uncover the exhaust ports during reciprocation of the pistons within the cylinders, and one or more rotary exhaust valves associated with each exhaust port. The exhaust valves can be configured to rotate around a valve axis that is substantially parallel to an axis of rotation of a crank shaft of the engine. Each exhaust valve at least partially obstructs the associated exhaust port during a portion of the exhaust valve's rotation about the valve axis while the associated exhaust port is at least partially uncovered by the associated piston, thereby trapping fresh charge within the combustion chamber.