A three-cycle radial vane piston internal combustion engine comprising an engine block integrating a cylindrical power casing, drive box, and compressor. The power casing includes air inlet, fuel injector, spark plug, and exhaust outlet ports, and houses three or more meshed radial vane pistons mounted on centrally located coaxial shafts forming three or more chambers. The coaxial shafts extend into the drive box, each shaft having a radial crank with a bushing at its end. The bushing is fitted with a slider/shaft joint unit with the slider side is sliding within radial slots of an off-center flywheel. The crank, slider/shaft joint, radial slot, and off-center flywheel form an inverted slider-crank mechanism linking the vanes' motion through the flywheel slots. The cyclically varying chamber volumes enable combined intake and exhaust, compression, and power strokes. The engine incorporates a compressed air kick start system for starting without a starter motor.