Abstract: A balanced motor two-stroke cycle engine having a linear drive includes a sealed gearcase secured to a cylinder housing having a plurality of concentric cylinders. The sealed gearcase includes a fixed ring gear, a pinion gear whose diameter is equal to the radius of the ring gear, a hub on which a piston rod is journaled for rotation, and two sets of counterweights. The piston rod moves in a linear fashion as the pinion gear rotates inside the fixed ring gear. The piston rod extends into the innermost cylinder, and a piston secured to the piston rod reciprocates linearly in the innermost cylinder. A chamber between the piston and the gearcase receives a flow of air and the air is transferred to the cylinder beneath the piston through a plurality of ports or apertures for compression. Fuel is injected into the cylinder from a pump chamber by a diaphragm that moves in response to air pressure in the cylinder beneath the piston.

Abstract: A balanced motor two-stroke cycle engine having a linear drive includes a sealed gearcase secured to a cylinder housing having a plurality of concentric cylinders. The sealed gearcase includes a fixed ring gear, a pinion gear whose diameter is equal to the radius of the ring gear, a hub on which a piston rod is journaled for rotation, and two sets of counterweights. The piston rod moves in a linear fashion as the pinion gear rotates inside the fixed ring gear. The piston rod extends into the innermost cylinder, and a piston secured to the piston rod reciprocates linearly in the innermost cylinder. Different embodiments of exhaust valve structure are illustrated in different embodiments, and an external combustion chamber embodiment is also illustrated.