Abstract: A transmission includes a forward shift drum and an overlying and coaxial reverse shift drum. The drums are rotatable, but not longitudinally translatable with respect to each other. The drums each include lead grooves for guiding a shift fork pin therealong in portions of the grooves which overlap and intersect each other. When one of the lead grooves guides the shift fork pin into a gear position, the other lead groove serves as a stop, so that unintentional engagement of remaining gears with the drive shaft is prevented without the use of a separate special lock mechanism.

Abstract: A transmission system for a motorcycle or motorized tricycle, comprising a main gearbox 3 having multiple gear steps, a sub gearbox 4 coupled to the main gearbox having two widely spaced forward gears GL, GH an one reverse gear GR; and one shift lever 14 controlling the selection of the gears in the sub gearbox. The reverse gear may be interlocked with the neutral and lowest speed gear of the main gearbox.

Abstract: A transmission system for a motorcycle or motorized tricycle, comprising a main gearbox 3 having multiple gear steps, a sub gearbox 4 coupled to the main gearbox having two widely spaced forward gears GL, GH and one reverse gear GR; and one shift lever 14 controlling the selection of the gears in the sub gearbox. The reverse gear may be interlocked with the neutral and lowest speed gear of the main gearbox.

Abstract: A sealing structure of a rotary valve in an internal combustion engine in which a recess is formed either at an opening portion of a rotary valve proper or at an opening portion of a combustion chamber in a housing and in which a seal member slidably fitted in the recess is resiliently pushed against the opposing part by means of a spring member. An annular resilient member is interposed between the lower surface of the seal member and the opposing bottom surface of the recess in such a manner that the two ends of the resilient member are respectively in contact with the surfaces of the seal member and the recess. Thereby, the contact pressure at the ends of the resilient member is increased by utilizing the gas pressure in the combustion chamber. Further, the pushing force of the seal member against the opposing part is increased, so as to enhance sealing efficiency.

Abstract: A rotary valve in an internal combustion engine in which the rotary valve proper is formed so as to be hollow and cylindrical and arranged in such a manner that its inner space forms a portion of an intake passage and a portion of an exhaust passage, which portions are separated from each other. In this manner, the valve proper, exhaust passage, and a housing are effectively cooled, and sealing for the rotary valve proper is made effectively and positively.

Abstract: An internal combustion piston engine drives a rotary supercharger of the positive displacement substantially continuous flow type, the supercharger turning in proportion to the engine speed. A power control valve is positioned upstream from the supercharger for controlling the flow of air-fuel mixture to said supercharger. Objectionable fluctuations in speed of the engine when idling are minimized by a secondary valve operatively positioned between the supercharger and a valved intake passage leading to the combustion chamber of the engine. The operation of the secondary valve and the power control valve are coordinated so that the secondary valve remains in idle position when the engine is idling but remains in open position during all other engine operating conditions.