Abstract: A structure for transmitting the power of a motorcycle engine includes an intermediate shaft arranged between a crankshaft and an input shaft of a transmission, and a method for making the structure. The structure and the method have the objective of shortening the distances between these three shafts, improving workability of assembling, and providing freedom of setting a speed reduction ratio. An intermediate shaft driven gear and an intermediate shaft driving gear having a diameter smaller than the intermediate shaft driven gear and are mounted in two steps, with the former overlaid on the latter, on an end of the intermediate shaft projecting outside a right case. Similarly, the intermediate shaft driven gear is engaged with a primary gear of the crankshaft, and the intermediate shaft driving gear is engaged with a primary driven gear of the input shaft at a location outside the right case.

Abstract: To enable the miniaturization of a crankcase side cover to lighten it in a casing of an engine and to enable the reduction of the area of each joined face to make performance for sealing the joined faces of a crankcase and the crankcase side cover satisfactory. In a casing of an engine composed of a crankcase, a crankcase side cover the inner end of which is joined to one side end of the crankcase and which covers a primary reduction gear and a clutch cover which is joined to the outer end of the crankcase side cover and which houses a clutch together with the crankcase side cover, the inside diameter d of the joined faces of a clutch enclosure enclosing the clutch of the crankcase side cover and the crankcase is set so that the inside diameter is smaller than the outside diameter D of a clutch outer in the clutch.

Abstract: A structure for transmitting the power of a motorcycle engine includes an intermediate shaft arranged between a crankshaft and an input shaft of a transmission, and a method for making the structure. The structure and the method have the objective of shortening the distances between these three shafts, improving workability of assembling, and providing freedom of setting a speed reduction ratio. An intermediate shaft driven gear and an intermediate shaft driving gear having a diameter smaller than the intermediate shaft driven gear and are mounted in two steps, with the former overlaid on the latter, on an end of the intermediate shaft projecting outside a right case. Similarly, the intermediate shaft driven gear is engaged with a primary gear of the crankshaft, and the intermediate shaft driving gear is engaged with a primary driven gear of the input shaft at a location outside the right case.

Abstract: A structure for transmitting the power of a motorcycle engine includes an intermediate shaft arranged between a crankshaft and an input shaft of a transmission, and a method for making the structure. The structure and the method have the objective of shortening the distances between these three shafts, improving workability of assembling, and providing freedom of setting a speed reduction ratio. An intermediate shaft driven gear and an intermediate shaft driving gear having a diameter smaller than the intermediate shaft driven gear and are mounted in two steps, with the former overlaid on the latter, on an end of the intermediate shaft projecting outside a right case. Similarly, the intermediate shaft driven gear is engaged with a primary gear of the crankshaft, and the intermediate shaft driving gear is engaged with a primary driven gear of the input shaft at a location outside the right case.

Abstract: A mounting structure for a cam-type torque damper is provided to ease the assembling thereof, improve the maintenance properties thereof and prevent the variation in thrust direction restricting position due to loosening or the like. A collar is spline connected to an axial end of a crankshaft, and a primary gear, a lifter, a spring and a spring holder are fitted on the collar in that order. A cotter is fitted in a groove in the collar so as to restrict the spring holder with respect to the thrust direction position to thereby assemble the cam-type torque damper into a small assembly. The cam-type torque damper so made to be a small assembly is then fastened to the axial end of the crankshaft with a bolt. A concave cam is formed in a side of the primary gear, and a convex cam provided in an axial end portion of the lifter is brought into mesh engagement with the concave cam.

Abstract: To enable the miniaturization of a crankcase side cover to lighten it in a casing of an engine and to enable the reduction of the area of each joined face to make performance for sealing the joined faces of a crankcase and the crankcase side cover satisfactory. In a casing of an engine composed of a crankcase, a crankcase side cover the inner end of which is joined to one side end of the crankcase and which covers a primary reduction gear and a clutch cover which is joined to the outer end of the crankcase side cover and which houses a clutch together with the crankcase side cover, the inside diameter d of the joined faces of a clutch enclosure enclosing the clutch of the crankcase side cover and the crankcase is set so that the inside diameter is smaller than the outside diameter D of a clutch outer in the clutch.

Abstract: An oil pump is formed by a main body portion, a base, and a pump cover, and is provided with a rotor rotational shaft. The oil pump is formed with a main pump and a sub pump. The oil pump is attached to bond with a wall face of a thick-walled portion of a crankcase. A relief valve chamber is provided in the thick-walled portion in parallel with the rotor rotational shaft. A relief valve is contained therein in parallel with the rotor rotational shaft. A surrounding space in the relief valve chamber is directly connected to a pumping portion of the oil pump. This combination of elements and configuration provides for an oil pump that operates with efficiency, and that is small in size, light in weight.

Abstract: A structure for transmitting the power of a motorcycle engine includes an intermediate shaft arranged between a crankshaft and an input shaft of a transmission, and a method for making the structure. The structure and the method have the objective of shortening the distances between these three shafts, improving workability of assembling, and providing freedom of setting a speed reduction ratio. An intermediate shaft driven gear and an intermediate shaft driving gear having a diameter smaller than the intermediate shaft driven gear and are mounted in two steps, with the former overlaid on the latter, on an end of the intermediate shaft projecting outside a right case. Similarly, the intermediate shaft driven gear is engaged with a primary gear of the crankshaft, and the intermediate shaft driving gear is engaged with a primary driven gear of the input shaft at a location outside the right case.

Abstract: An oil pump is formed by a main body portion, a base, and a pump cover, and is provided with a rotor rotational shaft. The oil pump is formed with a main pump and a sub pump. The oil pump is attached to bond with a wall face of a thick-walled portion of a crankcase. A relief valve chamber is provided in the thick-walled portion in parallel with the rotor rotational shaft. A relief valve is contained therein in parallel with the rotor rotational shaft. A surrounding space in the relief valve chamber is directly connected to a pumping portion of the oil pump. This combination of elements and configuration provides for an oil pump that operates with efficiency, and that is small in size, light in weight.

Abstract: A mounting structure for a cam-type torque damper is provided to ease the assembling thereof, improve the maintenance properties thereof and prevent the variation in thrust direction restricting position due to loosening or the like. A collar is spline connected to an axial end of a crankshaft, and a primary gear, a lifter, a spring and a spring holder are fitted on the collar in that order. A cotter is fitted in a groove in the collar so as to restrict the spring holder with respect to the thrust direction position to thereby assemble the cam-type torque damper into a small assembly. The cam-type torque damper so made to be a small assembly is then fastened to the axial end of the crankshaft with a bolt. A concave cam is formed in a side of the primary gear, and a convex cam provided in an axial end portion of the lifter is brought into mesh engagement with the concave cam.