Abstract: In an internal combustion engine with a balancer including a crankcase having a pair of wall portions, a crankshaft supported for rotation on the wall portions and having a balancer driving gear wheel provided thereon, and a balancer shaft supported for rotation by the wall portions and having a balancer driven gear wheel provided thereon, both gear wheels are disposed between the wall portions. A positioning mark including a set of marks provided on side faces in the same direction of the gear wheels is disposed near to pitch circles of both gear wheels. At a position opposing to both side faces of the one wall portion on the side opposing to the positioning mark on the pitch circles of both gear wheels, a through-hole extending through the one side wall is provided to permit the positioning mark to be visually observed through the through-hole.

Abstract: A lubrication structure for a bearing section of an internal combustion engine including a crankcase having a wall portion, a bearing secured to the wall portion, a rotational shaft supported for rotation by the bearing, and a bearing restriction member disposed on a side face of an outer race portion of the bearing and configured to suppress coming off of the bearing, wherein an oil receiving portion formed in a swollen state on the wall portion along an outer periphery on the outer side of an outer periphery below the center axis of the bearing, and an oil reserve section is provided so as to extend over the oil receiving portion and the bearing restriction member.

Abstract: A lubrication structure for a bearing section of an internal combustion engine including a crankcase having a wall portion, a bearing secured to the wall portion, a rotational shaft supported for rotation by the bearing, and a bearing restriction member disposed on a side face of an outer race portion of the bearing and configured to suppress coming off of the bearing, wherein an oil receiving portion formed in a swollen state on the wall portion along an outer periphery on the outer side of an outer periphery below the center axis of the bearing, and an oil reserve section is provided so as to extend over the oil receiving portion and the bearing restriction member.

Abstract: In an internal combustion engine with a balancer including a crankcase having a pair of wall portions, a crankshaft supported for rotation on the wall portions and having a balancer driving gear wheel provided thereon, and a balancer shaft supported for rotation by the wall portions and having a balancer driven gear wheel provided thereon, both gear wheels are disposed between the wall portions. A positioning mark including a set of marks provided on side faces in the same direction of the gear wheels is disposed near to pitch circles of both gear wheels. At a position opposing to both side faces of the one wall portion on the side opposing to the positioning mark on the pitch circles of both gear wheels, a through-hole extending through the one side wall is provided to permit the positioning mark to be visually observed through the through-hole.

Abstract: In a multiple disc clutch apparatus 10, a cam member 41 which is disposed on a side of a clutch inner member 16 is formed into an annular shape. The cam member 41 extends in a radial direction so that an outer circumferential surface of the cam member 41 is brought into abutment with a cylindrical face 19d on an inner circumferential surface of a clutch center member 19.

Abstract: A multi-plate clutch system includes an outer clutch member having a plurality of first clutch plates thereon, a central spool having a plurality of second clutch plates thereon interspaced with the first clutch plates. The clutch system also includes a cam mechanism including a protruding cam and a recessed cam. The protruding cam and the recessed cam respectively include first inclined faces and second inclined faces, which are inclined in the same direction with respect to the circumferential direction. The protruding cam is thus brought into a point contact with the recessed cam during clutch engagement. As such, the multi-plate clutch system can maintain constant variable characteristics of the clutch capacity even when there is a variation in processing accuracy at the time of the production.

Abstract: In a multiple disc clutch apparatus 10, a cam member 41 which is disposed on a side of a clutch inner member 16 is formed into an annular shape. The cam member 41 extends in a radial direction so that an outer circumferential surface of the cam member 41 is brought into abutment with a cylindrical face 19d on an inner circumferential surface of a clutch center member 19.

Abstract: A dog clutch includes a first engagement face and a second engagement face provided on a surface of a driving rotor and a driven rotor with the two surfaces being opposite each other. The first engagement face engaging with its counterpart when a driving force of the driving members is generated. The second engagement face engaging with its counterpart when the driving member receives the driving force from the driven member. The strength of the engagement portion is balanced reflecting the operational torque changing as a power transmission direction changes. A projection drawing to a plane perpendicular to a rotational axis of a driving rotor and of a driven rotor, the inward extension line of the first engagement face passes through a position offset from the position representing the rotational axis, and the inward extension line of the second engagement face passes through the position representing the rotational axis.

Abstract: A clutch for effectively prevents a clutch outer from tilting at the time when torque is varied. The clutch includes damper springs for transmitting, to a clutch outer, torque inputted to a driven gear, and a thrust washer for regulating positional change of a position of the clutch outer with respect to the driven gear in a direction of the shaft axis. The thrust washer is disposed between the driven gear and the clutch outer in an axial direction. The thrust washer is disposed only outward of the damper springs in a radial direction.

Abstract: An accessories arrangement structure for an internal combustion engine for securing a banking angle, increasing a degree of the freedom of the layout, concentrating heavy accessories and an overhanging part of the internal combustion engine, enhancing the maneuverability of the vehicle and reducing the size of the engine. An accessories arrangement structure of an internal combustion engine for a motorcycle includes an oil cooler and an oil filter that are attached together with a balancer in a lower part wherein the front of a crankcase that journals a crankshaft directed in a vehicular width direction, in which the oil cooler and the oil filter are attached to the front in a vehicular traveling direction of the crankcase project with a balancer, the oil cooler and the oil filter being adjacent in a front view of the vehicle and arranged abreast in parallel with a crankshaft.

Abstract: A multi-plate clutch system includes an outer clutch member having a plurality of first clutch plates thereon, a central spool having a plurality of second clutch plates thereon interspaced with the first clutch plates. The clutch system also includes a cam mechanism including a protruding cam and a recessed cam. The protruding cam and the recessed cam respectively include first inclined faces and second inclined faces, which are inclined in the same direction with respect to the circumferential direction. The protruding cam is thus brought into a point contact with the recessed cam during clutch engagement. As such, the multi-plate clutch system can maintain constant variable characteristics of the clutch capacity even when there is a variation in processing accuracy at the time of the production.

Abstract: In an engine having a generator mounted thereon, an oil passage is formed within the engine's crankcase to supply oil to an oil jet for cooling one or more pistons. In addition, oil is supplied to an oil jet for cooling the generator, using the oil passage in common with the oil supply for cooling the piston, without requiring a separate, dedicated oil passage for the generator. The cooling oil delivery structure is provided for cooling the generator which is located at one end of the crankshaft. The oil passage for cooling pistons, which includes an oil jet for cooling each respective piston by jetting oil to the piston, is arranged on an axis substantially parallel to the crankshaft. A generator-cooling oil jet is provided on the crankcase at a terminal end of, and in fluid communication with the oil passage for cooling the pistons.

Abstract: An internal combustion engine is provided with an internal piston cooling system that jets oil from an oil jet onto a surface of a piston during engine operation, to effectively cool the piston. In the piston cooling system of the internal combustion engine, each piston being arranged to reciprocate in a cylinder bore of a cylinder block, and oil is jetted from individual oil jets to each piston, respectively. An oil reservoir is formed in a crankcase journal wall, that journals a crankshaft of the engine. In the crankcase, oil supply passages are provided for supplying oil from a hydraulic supply source to the oil reservoir, and in turn, oil is operatively supplied from the oil reservoir to the oil jets via a passageway.

Abstract: An accessories arrangement structure for an internal combustion engine for securing a banking angle, increasing a degree of the freedom of the layout, concentrating heavy accessories and an overhanging part of the internal combustion engine, enhancing the maneuverability of the vehicle and reducing the size of the engine. An accessories arrangement structure of an internal combustion engine for a motorcycle includes an oil cooler and an oil filter that are attached together with a balancer in a lower part wherein the front of a crankcase that journals a crankcase directed in a vehicular width direction, in which the oil cooler and the oil filter are attached to the front in a vehicular traveling direction of the crankcase project with a balancer, the oil cooler and the oil filter being adjacent in a front view of the vehicle and arranged abreast in parallel with a crankshaft.

Abstract: In an engine having a generator mounted thereon, an oil passage is formed within the engine's crankcase to supply oil to an oil jet for cooling one or more pistons. In addition, oil is supplied to an oil jet for cooling the generator, using the oil passage in common with the oil supply for cooling the piston, without requiring a separate, dedicated oil passage for the generator. The cooling oil delivery structure is provided for cooling the generator which is located at one end of the crankshaft. The oil passage for cooling pistons, which includes an oil jet for cooling each respective piston by jetting oil to the piston, is arranged on an axis substantially parallel to the crankshaft. A generator-cooling oil jet is provided on the crankcase at a terminal end of, and in fluid communication with the oil passage for cooling the pistons.

Abstract: An internal combustion engine is provided with an internal piston cooling system that jets oil from an oil jet on to a surface of a piston during engine operation, to effectively cool the piston. In the piston cooling system of the internal combustion engine, each piston being arranged to reciprocate in a cylinder bore of a cylinder block, and oil is jetted from individual oil jets to each piston, respectively. An oil reservoir is formed in a crankcase journal wall, that journals a crankshaft of the engine. In the crankcase, oil supply passages are provided for supplying oil from a hydraulic supply source to the oil reservoir, and in turn, oil is operatively supplied from the oil reservoir to the oil jets via a passageway.

Abstract: A dog clutch includes a first engagement face and a second engagement face provided on a surface of a driving rotor and a driven rotor with the two surfaces being opposite each other. The first engagement face engaging with its counterpart when a driving force of the driving members is generated. The second engagement face engaging with its counterpart when the driving member receives the driving force from the driven member. The strength of the engagement portion is balanced reflecting the operational torque changing as a power transmission direction changes. A projection drawing to a plane perpendicular to a rotational axis of a driving rotor and of a driven rotor, the inward extension line of the first engagement face passes through a position offset from the position representing the rotational axis, and the inward extension line of the second engagement face passes through the position representing the rotational axis.

Abstract: A relief valve includes a cylindrical valve housing attached to an engine body continuously with a relief passage and an outlet provided in an axially intermediate portion thereof. A valve body is slidably fitted to the valve housing so as to allow the relief passage to communicate with the outlet as an oil pressure in the relief passage becomes equal to and exceeds a predetermined oil pressure. A skirt includes an upper end portion fixed to the valve housing above the outlet for guiding oil discharged from the outlet downward. The relief valve exerts a reliable defoaming function in response to an increase in the oil discharged from the outlet and an increase in an ejection pressure thereof while avoiding an increase in the size of the skirt. An annular recessed portion is formed on an outer circumference of the intermediate portion of the valve housing below the outlet.

Abstract: A clutch for effectively prevents a clutch outer from tilting at the time when torque is varied. The clutch includes damper springs for transmitting, to a clutch outer, torque inputted to a driven gear, and a thrust washer for regulating positional change of a position of the clutch outer with respect to the driven gear in a direction of the shaft axis. The thrust washer is disposed between the driven gear and the clutch outer in an axial direction. The thrust washer is disposed only outward of the damper springs in a radial direction.

Abstract: In a cylinder head of an internal combustion engine, a plug hole for mounting an ignition plug is formed along a cylinder axis and an intake port and an exhaust port are respectively formed at both sides of the plug hole while sandwiching the cylinder axis therebetween. The cylinder head further includes an intake valve which opens or closes the intake port and an exhaust valve which opens or closes the exhaust port. In such a constitution, a cross-sectional shape of a flow passage of an outlet of the exhaust port is an oval shape extending in the horizontal direction and a water drain hole of the plug hole is formed below the exhaust port.