Abstract: An internal combustion engine of the four cycle reciprocating piston type wherein intake and exhaust of working fluid and combustible fuel into the engine is primarily by means of valves in the cylinder head, and secondarily by means of an intake port in open communication with the lower portion of the cylinder chamber for the induction of additional gases for the support of combustion, and preferably a combustible mixture controlled by valve means for induction only.

Abstract: A rear suspension for motorcycles which employs primary and secondary torsion springs operating on the rotative axis of the horizontally disposed and rearwardly trailing fork carrying the powered traction wheel. The two springs are of selected resilience and are quickly replaceable without disassembly of the suspension system, and each is adjustable for controlling the normal vehicle height and pitch attitude to be subjected to varying loads. Load application to this rear suspension system is substantially central of the vehicle and with the result that radius of gyration is minimized, unsprung weight is reduced, and with improved dynamics characterized by a spring-stop snubbing action resulting in increased traction and ground engagement capability for superior handling.