Abstract: A multiple-cycle engine is provided that alternates between two-cycle and four-cycle operation in response to measured engine conditions. Each piston is ball and socket mounted to allow the piston to be trained to five positions by a training block within the cylinder wall. Intake and scavenging port runners and a piston port align to place a fuel charge in the combustion chamber in the first position, while the second position seals it for compression and ignition. A piston exhaust vent aligns with an exhaust port in the third position to discharge the exhaust for completion of four-cycle operation. In a fourth position, the intake port and a second scavage port runner align to fuel the combustion chamber, while exhaust leaves through a second piston exhaust vent in alignment with the exhaust port incoming charge is scavenged by the suction of a megaphone type exhaust pipe. In a fifth position, the chamber is sealed for compression and ignition for completion of two-cycle operation.