Abstract: A cylinder head, for an internal combustion engine, enhances engine efficiency while ensuring favorable coolant flow. The cylinder head includes a main casting body 41 having a hollow water jacket formed therein, to allow coolant flow therethrough. The main casting body 41 includes a plurality of cylindrical plug hole walls 91 which have plug holes 90 formed therein inside a head-side water jacket 60. The cylinder head also includes partitions 100, formed inside the head-side water jacket 60, and these partitions connect the plug hole walls 91 together form a dividing wall, which divides the water jacket into an exhaust port section and an intake port section. Coolant entering the water jacket is divided into two substreams, which flow initially in substantially opposite directions, and which are reunited after flowing around opposite ends of the dividing wall.

Abstract: A method of improving wear-resistance and anti-seizing properties of slide surface of machineries, such as outer slide surfaces of piston pins of vehicle engines, wherein slide surfaces of iron or steel base materials of machineries are first processed carburizing, then the carburized surfaces are plated with chromium, and next the chromium-plated surfaces undergo impulses fine peening to produce lubricant-retaining cavities on the slide surfaces, which include fine cavities in the form of depressions in the chromium-plating layer and relatively large cavities produced by exfoliation of the chromium-plating layer.

Abstract: A multi-cylinder internal combustion engine draws oil from an oil reservoir with an oil pump, and supplies oil to individual areas of the engine, after passing the oil through an oil filter and an oil cooler. A filter case containing an element of the oil filter is mounted to a side surface of the engine to facilitate the removal and replacement of the case. The oil cooler and a balancer are each respectively mounted to a front central portion of the internal combustion engine to enable oil cooling by an air-cooling effect of a running airflow, and to balance weight in the left-right direction of the internal combustion engine. Oil discharged from the oil cooler is introduced to a substantially central portion of the main gallery, to achieve uniformity of oil pressure supplied to individual bearing portions and uniformity of cooling of the individual bearing portions.

Abstract: A torque transmitting device having a rotating shaft and a gear connected to the shaft. The gear transmits the torque between the rotating shaft and the gear. A splined portion and a centering inner circumferential surface portion formed in the inner periphery of the gear are engaged with the splined portion and the centering outer circumferential surface portion formed on the outer periphery of the rotating shaft. This arrangement minimizes noise due to gear runout, and reduces wear in the gear.

Abstract: To provide a high performance four-stroke internal combustion engine wherein an increase in a side of a cylinder head is prevented and a valve resting mechanism is provided for a valve lifter. In a four-stroke internal combustion engine with a valve resting mechanism includes a valve lifter having a valve resting mechanism interposed between a valve motion cam and a stem of a poppet valve and a valve lifter spring is provided for biasing the valve lifter in a direction in which the valve lifter is normally held in contact with the valve motion cam. A slide pin holder is pressed against the valve lifter by a spring force of the valve lifter spring that is provided on the valve lifter while a shim portion having a predetermined thickness for controlling a relative positional relationship with the valve lifter is formed integrally with a valve lifter top wall.

Abstract: A cylinder head for an internal combustion engine in which any of a plurality of valve guides for guiding intake and exhaust poppet valves provided with valve lifters can be press-fitted in fitting holes of the cylinder head with a substantially uniform press fit force. At least one valve guide is fitted at a different depth in the cylinder head than others of the guides valves. The intake and exhaust poppet valves have substantially uniform thicknesses in the respective longitudinal directions of the valve guides. An idle fitting hole with an inner diameter greater than an outer diameter of the valve guides is formed above one of the fitting holes which is formed deeper in the cylinder head than the other fitting holes, the idle fitting hole extending upward to a lower side of a valve spring.

Abstract: For the purpose of improving wear-resistance and anti-seizing property of slide surfaces of machineries, such as outer slide surfaces of piston pins of vehicle engines, slide surfaces of iron or steel base materials of machineries are first processed by carburizing, then the carburized surfaces are plated with chromium, and next the chromium-plated surfaces undergo impulses by shot peening to produce lubricant-retaining cavities on the slide surfaces, which include fine cavities in the form of depressions in the chromium-plating layer and relatively large cavities produced by exfoliation of the chromium-plating layer.

Abstract: A cylinder head in which any valve guide can be press-fitted in the cylinder head with a substantially uniform press fit force based upon the cylinder head in which at least one valve guide out of a plurality of valve guides for respectively guiding intake and exhaust poppet valves of an OHC four-stroke internal combustion engine are provided with valve lifters so that the valve guide can slide in a direction in which each valve that is opened or closed is fitted differently in the depth of a fitted part.

Abstract: To provide a high performance four-stroke internal combustion engine wherein an increase in a side of a cylinder head is prevented and a valve resting mechanism is provided for a valve lifter. In a four-stroke internal combustion engine with a valve resting mechanism includes a valve lifter having a valve resting mechanism interposed between a valve motion cam and a stem of a poppet valve and a valve lifter spring is provided for biasing the valve lifter in a direction in which the valve lifter is normally held in contact with the valve motion cam. A slide pin holder is pressed against the valve lifter by a spring force of the valve lifter spring that is provided on the valve lifter while a shim portion having a predetermined thickness for controlling a relative positional relationship with the valve lifter is formed integrally with a valve lifter top wall.

Abstract: A clutch having a friction spring for exerting a frictional torque for restraining resonance of the damper spring utilizing a small pressing force. The friction spring is disposed at a portion of the clutch member which is radially outward from the damper spring. This arrangement reduces the amount of spring force required of the friction spring. Also, the contact areas between the clutch member and the driven gear are located radially outwardly of the damper spring, which increases the annular contact area between the driven gear and the clutch member, and reduces wear.

Abstract: A lubricating oil feed passage in a crank shaft, having lubricating oil passages formed in the crank shaft and having an inlet end and an outlet end which is open to a connection surface of a crank pin for connection with a connecting rod, a bolt secured to an end portion of the crank shaft so as to project in an axial direction of the crank shaft from an end face of the shaft end portion, and a lubricating oil introducing passage formed axially through the bolt and connected to the inlet end.

Abstract: In an overhead cam shaft engine with a starter motor, the starter motor is to be mounted to a front face of a crank case at a position close to a cylinder, thereby creating a space on the front face of the crank case, while preventing interference between a gear train for the transfer of rotation of the starter motor and a cam shaft driving mechanism. An overhead cam shaft type engine includes a starter motor, having a cam shaft driving mechanism disposed on one end side of a crank shaft and a gear train for the transfer of rotation of a starter motor. The gear train is disposed on an opposite side of the crank shaft. The axis of a gear shaft of at least one gear of plural gears which constitute the gear train is positioned above a crank case dividing plane. Furthermore, the starter motor is mounted to a front face of a lower crank case at an upper position close to a cylinder, and an oil filter is mounted in a space thus created below the starter motor on the front face of the lower crank case.

Abstract: To enable preventing interference between a honing machine and a journal wall, avoiding large-sizing of a cylinder block and tilting a front cylinder part so that the upper end is as low as possible in a vehicular V-type internal combustion engine wherein the front cylinder part arranged on the front side in a vehicular travel direction and a rear cylinder part arranged on the rear side in the vehicular travel direction are arranged so that they form an approximate V-shape. A front cylinder part is tilted so that the upper end is lower than that of a rear cylinder part and a bent part bent on the side distant from a central position is formed in a part corresponding to a front cylinder hole of a journal wall arranged on the side displaced from the central position between both journal walls of the front cylinder hole.

Abstract: A crankcase for a motorcycle is divided into an upper half and a lower half. A crankshaft, a main shaft, a counter shaft, and a pivot portion are arranged substantially on a straight line along a parting plane P of the crankcase. An eccentric cam and a pivot collar are disposed in the pivot portion, and a rear swing arm is connected to the pivot shaft. The upper half and lower half are vertically mated to each other in front of and behind the pivot portion and then vertically fastened to each other. The center of the pivot collar is offset downwardly from the parting plane P.

Abstract: A structure for mounting a water pump to a water-cooled internal combustion engine in an easy manner. A water-cooled internal combustion engine in which the water pump is removably mounted to a side wall of the water-cooled internal combustion engine, is driven by power transmitted from a crank shaft to the water pump through a transmission mechanism, wherein a water pump driving member is arranged closer to a center of the internal combustion engine than an output driving member of the crank shaft. A water pump following member is driven by accepting the power from the water pump driving member and is rotatably mounted to a side wall of the internal combustion engine. A drive shaft of the water pump is removably spline fitted to splined aperture of the water pump following member.

Abstract: To prevent oil in which air is mixed from being led to an oil pump, preventing the number of parts from being increased in a lubricating system of an internal combustion engine wherein an oil relief valve dipped in oil in an oil pan is connected to a halfway part of a feed oil passage connecting the oil pan and an oil filter. An oil passage extends approximately horizontally and a connecting hole is provided with an axis approximately perpendicular to the oil passage for communicating with the oil passage which is open on the upper surface of a passage forming part formed in the passage forming part integrated with the bottom of an oil pan. An oil relief valve is coaxially connected to the connecting hole with the pressure receiving surface of its plunger directed downwardly. A wall part surrounds the oil relief valve on the side of an oil strainer and is integrated with the bottom of the oil pan.