An internal combustion engine using a two stroke cycle includes a pair of opposing cylinder units, each of which are located on opposing sides of a crankcase. In each cylinder unit is a cylinder with a piston disposed in the cylinder. Each piston is coupled to a piston rod that is aligned along an axis that passes through the center of each cylinder bore. The piston rods pass through the crankcase wall into the crankcase chamber, and are further coupled to a yoke. Each cylinder unit has an intake channel from the crankcase chamber to a cylinder intake port in the cylinder. As the piston traverses its upstroke in its cylinder, it creates a vacuum under the piston. At the top of its stroke a piston intake port becomes aligned with the cylinder intake port, allow fuel to be drawn into the cylinder under the piston. As a result, a continuous vacuum is experienced in the crankcase without the need for mechanical valving arrangements.