Abstract: In a V-belt type transmission having a V-belt entrained on a pulley, the pulley includes a fixed pulley half fixed to an end portion of a crankshaft and a movable pulley half supported on the crankshaft but axially slidable in opposition to the fixed pulley half. The fixed pulley half is secured with a bolt that is threaded and engaged with a female screw formed inside an end portion of the crankshaft. The V-belt type transmission is capable of securely clamping a fixed pulley half and is capable of preventing the entry of dust and water into a fixed pulley half threaded portion formed in an end portion of the crankshaft. This arrangement protects against the formation of rust and corrosion.

Abstract: In the breather structure of an internal combustion engine for vehicles, an outer cover is installed through a sound absorbing material for noise suppression on the outside of a body cover. The body cover covers a power unit including at least one of the internal combustion engine and a power transmission device. An outlet of the breather provided in the power unit opens at the sound absorbing material. The present invention provides a breather structure having a simplified construction, a short breather passage, and is capable of preventing entry and attachment of dust and debris into and onto the breather structure.

Abstract: A lubrication structure for an internal combustion engine including an oil pump provided at a first end of an oil pump shaft arranged parallel to a crankshaft. Oil passageways are formed from a side surface of a pump chamber of the oil pump to another end of the oil pump shaft in parallel with the oil pump shaft. An oil filter is provided facing towards the oil passageways. A communicating passageway extending vertically from the oil passageways to the oil filter is also provided. This arrangement provides a lubrication structure for an internal combustion engine with a high degree of freedom with respect to oil filter arrangement with a simple oil passageway that is easy to manufacture, requires relatively small space for arrangement, and thus makes it possible to reduce the size of the internal combustion engine.

Abstract: A motorcycle includes an engine mounted on a frame in a non-swingable manner. First and second rear arms are swingably supported by the engine about first and second coaxial swing axes, respectively. A rear wheel is rotatably supported between the first and second rear arms. The second rear arm includes front and rear arm members, which are supported swingably by the engine and support an axle of the rear wheel, respectively. The arm members are separably connected together to facilitate servicing and removal of the rear wheel.

Abstract: A belt type transmission improves the durability of a support portion of a driven shaft by reducing a load acting on a driven shaft, and improves the durability of the belt and reduces noise by suppressing vibration of a driven pulley. The belt type transmission includes a driven pulley having a fixed pulley piece and a movable pulley piece fitted to a driven shaft. The fixed pulley piece is rotatably supported, respectively, on the driven shaft and a bearing holder, being a constructional element of a transmission case. The bearing holder has a size overlapping only the driven pulley, and is coupled to a left case, which is a constructional element of the transmission case, in the vicinity of the driven pulley. As a result, the rigidity for supporting the fixed pulley piece on the driven side can be increased, thereby enabling suppression of vibration by the driven pulley.

Abstract: A cooling water circulating structure in an internal combustion engine is to be provided wherein cooling water can flow to every corner through a water jacket in a cylinder block and a water jacket in a cylinder head without being localized and thereby can cool the whole efficiently and which permits an easy layout of the water piping. A cooling water circulating structure in a multi-cylinder type internal combustion engine wherein a cooling water inlet and a cooling water outlet are formed side by side respectively in a side face of a cylinder block and a side face of a cylinder head both on the same side of the internal combustion engine close to a water pump, and a cylinder block-side water jacket and a cylinder head-side water jacket are brought into communication with each other through communication paths and are formed on the side opposite to the side close to the water pump, thereby allowing cooling water to circulate.

Abstract: To provide a balancer-fitting configuration for an internal combustion engine. With the balancer-fitting configuration of the present invention, the vibration control of an internal combustion engine with forward-inclined cylinders is achieved effectively by using paired balancers separated and disposed opposite to each other. Furthermore, the part of the crankcase behind the crankshaft is decreased in size in the longitudinal direction of the frame, and thereby, a space within which the rear wheel swings is obtained without enlarging the frame.

Abstract: A motorcycle includes an engine mounted on a frame in a non-swingable manner. First and second rear arms are swingably supported by the engine about first and second coaxial swing axes, respectively. A rear wheel is rotatably supported between the first and second rear arms. The second rear arm includes front and rear arm members, which are supported swingably by the engine and support an axle of the rear wheel, respectively. The arm members are separably connected together to facilitate servicing and removal of the rear wheel.

Abstract: In the breather structure of an internal combustion engine for vehicles, an outer cover is installed through a sound absorbing material for noise suppression on the outside of a body cover. The body cover covers a power unit including at least one of the internal combustion engine and a power transmission device. An outlet of the breather provided in the power unit opens at the sound absorbing material. The present invention provides a breather structure having a simplified construction, a short breather passage, and is capable of preventing entry and attachment of dust and debris into and onto the breather structure.

Abstract: In a V-belt type transmission having a V-belt entrained on a pulley, the pulley includes a fixed pulley half fixed to an end portion of a crankshaft and a movable pulley half supported on the crankshaft but axially slidable in opposition to the fixed pulley half. The fixed pulley half is secured with a bolt that is threaded and engaged with a female screw formed inside an end portion of the crankshaft. The V-belt type transmission is capable of securely clamping a fixed pulley half and is capable of preventing the entry of dust and water into a fixed pulley half threaded portion formed in an end portion of the crankshaft. This arrangement protects against the formation of rust and corrosion.

Abstract: A belt type transmission improves the durability of a support portion of a driven shaft by reducing a load acting on a driven shaft, and improves the durability of the belt and reduces noise by suppressing vibration of a driven pulley. The belt type transmission includes a driven pulley having a fixed pulley piece and a movable pulley piece fitted to a driven shaft. The fixed pulley piece is rotatably supported, respectively, on the driven shaft and a bearing holder, being a constructional element of a transmission case. The bearing holder has a size overlapping only the driven pulley, and is coupled to a left case, which is a constructional element of the transmission case, in the vicinity of the driven pulley. As a result, the rigidity for supporting the fixed pulley piece on the driven side can be increased, thereby enabling suppression of vibration by the driven pulley.

Abstract: A lubrication structure for an internal combustion engine including an oil pump provided at a first end of an oil pump shaft arranged parallel to a crankshaft. Oil passageways are formed from a side surface of a pump chamber of the oil pump to another end of the oil pump shaft in parallel with the oil pump shaft. An oil filter is provided facing towards the oil passageways. A communicating passageway extending vertically from the oil passageways to the oil filter is also provided. This arrangement provides a lubrication structure for an internal combustion engine with a high degree of freedom with respect to oil filter arrangement with a simple oil passageway that is easy to manufacture, requires relatively small space for arrangement, and thus makes it possible to reduce the size of the internal combustion engine.

Abstract: A cooling water circulating structure in an internal combustion engine is to be provided wherein cooling water can flow to every corner through a water jacket in a cylinder block and a water jacket in a cylinder head without being localized and thereby can cool the whole efficiently and which permits an easy layout of the water piping. A cooling water circulating structure in a multi-cylinder type internal combustion engine wherein a cooling water inlet and a cooling water outlet are formed side by side respectively in a side face of a cylinder block and a side face of a cylinder head both on the same side of the internal combustion engine close to a water pump, and a cylinder block-side water jacket and a cylinder head-side water jacket are brought into communication with each other through communication paths and are formed on the side opposite to the side close to the water pump, thereby allowing cooling water to circulate.

Abstract: To provide a balancer-fitting configuration for an internal combustion engine. With the balancer-fitting configuration of the present invention, the vibration control of an internal combustion engine with forward-inclined cylinders is achieved effectively by using paired balancers separated and disposed opposite to each other. Furthermore, the part of the crankcase behind the crankshaft is decreased in size in the longitudinal direction of the frame, and thereby, a space within which the rear wheel swings is obtained without enlarging the frame.