Abstract: An exhaust gas control apparatus (2) for an engine includes a filter case (3) that has an internal space; a filter (4) that is arranged in the filter case (3) and that purifies exhaust gas; and a mat (5) that is arranged, in a compressed state, between the filter case (3) and the filter (4). The filter (4) is arranged in the filter case (3) with a first flange (45) of the filter (4) engaged with the mat (5) and with a second flange (46) engaged with a retainer (6).

Abstract: An exhaust gas control apparatus (2) for an engine includes a filter case (3) that has an internal space; a filter (4) that is arranged in the filter case (3) and that purifies exhaust gas; and a mat (5) that is arranged, in a compressed state, between the filter case (3) and the filter (4). The filter (4) is arranged in the filter case (3) with a first flange (45) of the filter (4) engaged with the mat (5) and with a second flange (46) engaged with a retainer (6).

Abstract: A transmission structure of a power unit for a vehicle includes a clutch mechanism that is provided between a crankshaft and a main shaft, and is installed at the end of the main shaft outside a crankcase. The transmission includes a shift drum for driving shift forks for selectively establishing any of plural speeds. Both ends in an axial direction of the shift drum are rotatably supported by the crankcase. In the transmission structure, a sealed structure dedicated to the shift drum is not required, the number of parts is reduced and the assembly time is reduced. The shift drum, arranged in the maximum outside diameter of the clutch mechanism when viewed in a plane perpendicular to the axis of the main shaft, is assembled in the crankcase from the side of the clutch mechanism.

Abstract: A vehicular power unit including a drive-side transmission sprocket wheel provided on an end of an output shaft that protrudes from one side of a crankcase, an endless transmission belt for transmitting power to a driving wheel wound the sprocket wheel. The endless transmission belt transmits power from the crankshaft to a transmission housed in the crankcase. A water pump is arranged on the same side of the crankcase in a position between the crankshaft and the output shaft. Further, the water pump is disposed inside the drive-side transmission sprocket wheel in a direction along the axis of an output shaft. This configuration enables the vehicular power unit to be formed in a compact size in a direction along an axis of a crankshaft.

Abstract: A powertrain assembly having an improved engine configuration includes an engine and a transmission incorporated in a crankcase of the engine. The engine also comprises an oil pump and a water pump. The transmission is a cartridge-type shift drum transmission, which can be attached to or detached from a transmission attachment face which is a side face of the crankcase. The oil pump and the transmission attachment face are arranged in substantially non-overlapping relation in the side view of the engine. The water pump shaft is substantially coaxial with the oil pump shaft, and the water pump is positioned below a drive sprocket on the transmission countershaft so as to be overlapping while eliminating interference between them, allowing a close arrangement of components.

Abstract: The invention relates to a speed change gear drive for a transmission that can miniaturize an engine by improving the layout of parts. In particular, the invention relates to a speed change gear drive in which a change spindle is supported by a transmission case and a shift drum supported by the transmission case so that the shift drum can be rotated is driven by the turning of a change arm fixed to the change spindle, a shift fork the position of which is changed by the rotation of the shift drum and a shift fork rod that supports this shift fork are provided, and the change spindle and the shift fork rod are overlapped when the body of an engine is viewed from the side.

Abstract: By blocking off a partial passage opening in a lubricating oil supply passage of a transmission gear mechanism by attaching a transmission holder, an operation to block off the passage opening is omitted. Supply of lubricating oil to a main shaft and a counter shaft of a transmission gear mechanism is carried out using branched passages from a main gallery, and the branched passage constitutes a lubricating oil supply passage to the main shaft while the branched passage constitutes a lubricating oil supply passage to the counter shaft. A partial passage opening of the branched passage is then blocked up at the time of attaching a transmission holder to the transmission case, and in this way a lubricating oil supply passage to the counter shaft is formed.

Abstract: To advance the pivotally supporting point of a swing arm on a vehicle body frame, the distance in the forward and backward direction between a crankshaft and a countershaft of a transmission is decreased as much as possible thereby making the length of the swing arm great and sufficiently absorb upward and downward oscillation of a rear wheel to achieve stabilization of the vehicle body. A countershaft is disposed below a main shaft of the transmission while a shift drum is disposed rearwardly of the main shaft, and a driving sprocket wheel for driving a rear wheel is provided on the countershaft. An internal combustion engine is disposed on the vehicle body frame such that a rear portion of a transmission is positioned above a pivotally supporting point of a swing arm.

Abstract: A transmission structure of a power unit for a vehicle includes a clutch mechanism that is provided between a crankshaft and a main shaft, and is installed at the end of the main shaft outside a crankcase. The transmission includes a shift drum for driving shift forks for selectively establishing any of plural speeds. Both ends in an axial direction of the shift drum are rotatably supported by the crankcase. In the transmission structure, a sealed structure dedicated to the shift drum is not required, the number of parts is reduced and the assembly time is reduced. The shift drum, arranged in the maximum outside diameter of the clutch mechanism when viewed in a plane perpendicular to the axis of the main shaft, is assembled in the crankcase from the side of the clutch mechanism.

Abstract: A vehicular power unit including a drive-side transmission sprocket wheel provided on an end of an output shaft that protrudes from one side of a crankcase, an endless transmission belt for transmitting power to a driving wheel wound the sprocket wheel. The endless transmission belt transmits power from the crankshaft to a transmission housed in the crankcase. A water pump is arranged on the same side of the crankcase in a position between the crankshaft and the output shaft. Further, the water pump is disposed inside the drive-side transmission sprocket wheel in a direction along the axis of an output shaft. This configuration enables the vehicular power unit to be formed in a compact size in a direction along an axis of a crankshaft.

Abstract: To miniaturize an engine, to concentrate heavy masses and to reduce friction loss of a balancer. An engine crankcase structure in which a crankcase is vertically partitioned into an upper case and a lower case, each journal supporter is formed in the upper case and in the lower case so that the rotational axis of a crankshaft is located on a partition face of the crankcase in parallel with a direction of the width of the body. The crankshaft is supported so that the crankshaft can be rotated. An oil filter is directly attached to the lower case. An oil cooler and a secondary balancer are arranged in the front of the lower case.

Abstract: The cartridge type transmission is a transmission configured to be detachable and attachable from/to the crankcase, the main shaft is arranged on the cut surface BF of the crankcase, and the change spindle and the shift fork shaft are pivotally supported in the upper crankcase, which is positioned on the upper side of the cut surface BF. The counter shaft is pivotally supported in the lower crankcase, which is positioned on the lower side of the cut surface BF.

Abstract: To facilitate attachment/detachment work of an oil filter in a vehicle engine without increasing an outer dimension thereof, and to provide a uniform a supply of engine oil into an engine body. An oil filter is attached onto a front portion of the engine body so as to be detachable in a vehicle body width direction from a side face of the engine body. An exhaust pipe on a side on which an oil filter is attached is displaced to a center side in the vehicle body width direction so as not to overlap the oil filter when viewed from a front of the engine body.

Abstract: A gear position detecting system includes structure which facilitates mounting of the system, and minimizes direct contact of other objects with the system. The outer circumferential surface of a shift drum, turned by operation of a change pedal, is provided with lead grooves. Shift forks, engaged with the lead grooves, are moved in the left-right direction by turning of the shift drum, whereby shift gears are changed over, and a speed change desired by the rider is performed. A detection pin of a neutral safety switch, which is one of gear position sensors, is pushed in by a detection cam of a cam surface provided at the outer circumferential surface of the shift drum in the speed change operation position, whereby a neutral position is detected.

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 threaded fastener is configured to reduce stress experienced at a female threaded portion of a hole formed in an engine block, when the threaded fastener is inserted therein, and when an axial load is applied thereto. In a particular application, a crankshaft is supported between a top supporting wall of a crankcase and a bottom supporting wall of a main cap. The inventive bolt includes a hollowed-out male threaded portion, which fits into a hole in the top supporting wall. The male threaded portion includes an elastically deformable low-rigidity portion, in which a cylindrical hole is concentrically formed. The maximum allowable stress of the top supporting wall is less than that of the bolt, due to material considerations. The low-rigidity portion is placed overlapping the female threaded portion in the axial direction, and since it is elastically deformable, it helps alleviate the stress experienced by the female threaded portion.

Abstract: A cylinder block of a multicylinder engine, having a cylinder main body in which multiple cylinder bores are provided in parallel in an axial direction of a crankshaft, and a crankcase having plural journal walls. The crankcase is integrally provided with the cylinder main body, in which a communication hole extending in parallel to the axial line of the crankshaft is provided in the cylinder main body and the crankcase while at least a part of which is opened in the inner peripheral surface of the cylinder bore. This permits the cylinder block to be downsized, increases freedom of positional setting of the communication hole, and reduces ventilation resistance of air flow through the communication hole. A cut-processed member is expanded further outward from a piston slide surface and is formed along a radial direction of cylinder bores, in inner surfaces of the cylinder bores in at least portions closer to a piston at an open edge of a communication hole.

Abstract: The invention relates to a speed change gear drive for a transmission that can miniaturize an engine by improving the layout of parts. In particular, the invention relates to a speed change gear drive in which a change spindle is supported by a transmission case and a shift drum supported by the transmission case so that the shift drum can be rotated is driven by the turning of a change arm fixed to the change spindle, a shift fork the position of which is changed by the rotation of the shift drum and a shift fork rod that supports this shift fork are provided, and the change spindle and the shift fork rod are overlapped when the body of an engine is viewed from the side.

Abstract: A powertrain assembly having an improved engine configuration includes an engine and a transmission incorporated in a crankcase of the engine. The engine also comprises an oil pump and a water pump. The transmission is a cartridge-type shift drum transmission, which can be attached to or detached from a transmission attachment face which is a side face of the crankcase. The oil pump and the transmission attachment face are arranged in substantially non-overlapping relation in the side view of the engine. The water pump shaft is substantially coaxial with the oil pump shaft, and the water pump is positioned below a drive sprocket on the transmission countershaft so as to be overlapping while eliminating interference between them, allowing a close arrangement of components.

Abstract: The cartridge type transmission is a transmission configured to be detachable and attachable from/to the crankcase, the main shaft is arranged on the cut surface BF of the crankcase, and the change spindle and the shift fork shaft are pivotally supported in the upper crankcase, which is positioned on the upper side of the cut surface BF. The counter shaft is pivotally supported in the lower crankcase, which is positioned on the lower side of the cut surface BF.