Abstract: The present invention relates to a mounting structure for mounting firmly onto a rotating shaft a rotational force transmission member such as a chain sprocket, a gear, a belt pulley and the like. A drive sprocket as a rotational force transmission member is fitted into an end of the rotating shaft in a splined manner. A coned disc spring and a washer are positioned in sequence onto an outer face of the rotational force transmission member. The coned disc spring and the washer are supported and sandwiched by the screw fastening member to be screwed to an end of the rotating shaft and the rotational force transmission member.

Abstract: The invention is directed at a device that reduces the size of an engine in the direction along the axis of a crankshaft. More specifically, it relates to an engine starting system in which a part of a starting power transmission gear train is provided between one end portion of a crankshaft rotatably borne on a crankcase and a starter motor mounted to the crankcase is covered from the outside by an accessory coupled to and operated in conjunction with the crankshaft.

Abstract: The present invention relates to a mounting structure for mounting firmly onto a rotating shaft a rotational force transmission member such as a chain sprocket, a gear, a belt pulley and the like. A drive sprocket as a rotational force transmission member is fitted into an end of the rotating shaft in a splined manner. A coned disc spring and a washer are positioned in sequence onto an outer face of the rotational force transmission member. The coned disc spring and the washer are supported and sandwiched by the screw fastening member to be screwed to an end of the rotating shaft and the rotational force transmission member.

Abstract: The invention is directed at a device that reduces the size of an engine in the direction along the axis of a crankshaft. More specifically, it relates to an engine starting system in which a part of a starting power transmission gear train is provided between one end portion of a crankshaft rotatably borne on a crankcase and a starter motor mounted to the crankcase is covered from the outside by an accessory coupled to and operated in conjunction with the crankshaft.

Abstract: An internal combustion engine includes a crankshaft, a mainshaft, a clutch and a countershaft. The mainshaft is for a transmission and holds a transmission gear train. The clutch is disposed on the extension of the mainshaft. Furthermore, the countershaft for the transmission holds a gear train to mesh with the transmission gear train. Accordingly, power is transmitted in order from the crankshaft to the clutch, the mainshaft, and the countershaft. This arrangement ensures better knee-grip when the internal combustion engine is mounted on a vehicle and improves in-vehicle mountability by reducing the width and the axial length of the internal combustion engine. A mainshaft is disposed about immediately below the crankshaft. At least a part of the mainshaft is provided at the same axial position as the crankshaft.

Abstract: An internal combustion engine includes a crankshaft, a mainshaft, a clutch and a countershaft. The mainshaft is for a transmission and holds a transmission gear train. The clutch is disposed on the extension of the mainshaft. Furthermore, the countershaft for the transmission holds a gear train to mesh with the transmission gear train. Accordingly, power is transmitted in order from the crankshaft to the clutch, the mainshaft, and the countershaft. This arrangement ensures better knee-grip when the internal combustion engine is mounted on a vehicle and improves in-vehicle mountability by reducing the width and the axial length of the internal combustion engine. A mainshaft is disposed about immediately below the crankshaft. At least a part of the mainshaft is provided at the same axial position as the crankshaft.

Abstract: A two-cycle engine includes a port timing control device for varying a timing of the opening of an exhaust port by a piston. The port timing control means includes a first valve mounted within an exhaust passage adjacent to an upper end of the exhaust port and having a port timing control surface, a second valve mounted on a cylinder block between a cylinder head and the first valve and having a closure surface, and an urging member acting on the second valve to always urge it against the first valve. The first valve is operable to be angularly moved about an axis generally perpendicular to the axis of a cylinder into and out of an extended position where the control surface is disposed slightly below the upper end of the exhaust port to close a part of the exhaust port. The second valve is movable along a generally straight path into and out of an extended position where the closure surface closes that portion of the exhaust port lying between the upper end of the exhaust port and the first valve.