Abstract: An apparatus and method for a differential stroke combustion engine. The combustion engine including one or more two-part pistons, each two-part piston having a first piston part and a second piston part. The apparatus comprising: piston-lever element mechanically coupled to the second piston part; a plurality of cam-followers assemblies selectively coupleable with the piston-lever element for controlling operation of the second piston part; and wherein selective engagement of one or more cam-followers assemblies defines an operational mode of the second piston part.

Abstract: A system for achieving a four-stroke cycle with a single rotation of a crankshaft in an internal combustion engine having a crank, a crank pin freely rotatable in a slide block of a runner 40. The runner 40 pivots on a pin rigidly attached to the bottom of an engine casing. The runner also pivots on the end of a link arm. The link arm pivots on a pin of a piston moving in a cylinder along a predefined stroke.