Abstract: An air intake system for a saddle-ride vehicle for facilitating the intake of fresh air and for enabling a discharge of excess pressure in an air cleaner box. The system includes an air cleaner box with an air cleaner element housed in an air cleaner case and an intake duct connected to the air cleaner box with an intake port open toward a vehicle front side, in which the intake duct has a duct opening oriented outward of the duct between the intake port and the air cleaner box. The air cleaner box includes parts for connecting the intake duct, a connecting tube and also case openings oriented outward of the case.

Abstract: An intake structure for a motorcycle provides an intake air flow passage in a fuel tank arranged at an upper portion of a vehicle body. Left and right upper tank members are provided at an upper portion of a vehicle body. The upper tank portions are each provided with a recessed portion that is opened upward and inward. A tank wall, having an L-shaped cross section, extends rearward and subsequently downward. An upper opening of the recessed portion is covered with a lid member, and thereby, the recessed portion effectively functions as an air-supply passage leading to an interior portion of an air cleaners.

Abstract: An air intake system for a saddle-ride vehicle for facilitating the intake of fresh air and for enabling a discharge of excess pressure in an air cleaner box. The system includes an air cleaner box with an air cleaner element housed in an air cleaner case and an intake duct connected to the air cleaner box with an intake port open toward a vehicle front side, in which the intake duct has a duct opening oriented outward of the duct between the intake port and the air cleaner box. The air cleaner box includes parts for connecting the intake duct, a connecting tube and also case openings oriented outward of the case.

Abstract: An intake structure for a motorcycle provides an intake air flow passage in a fuel tank arranged at an upper portion of a vehicle body. Left and right upper tank members are provided at an upper portion of a vehicle body. The upper tank portions are each provided with a recessed portion that is opened upward and inward. A tank wall, having an L-shaped cross section, extends rearward and subsequently downward. An upper opening of the recessed portion is covered with a lid member, and thereby, the recessed portion effectively functions as an air-supply passage leading to an interior portion of an air cleaners.

Abstract: A crankcase of an internal combustion engine with a reduced size for an oil pan. A crankcase is composed of an upper crankcase half and a lower crankcase half. A wall portion for defining a space X as a flow passage for a lubricating oil is formed below a journal bolt mounting surface of the lower crankcase half. A tool insertion hole for insertion of a tool for tightening a journal bolt is formed through the wall portion.

Abstract: A clutch control device for obtaining a good shift shock reducing effect regardless of a change in clutch engagement point. A target NeV database stores a target NeV map as a target value of the ratio between an engine speed (Ne) and a vehicle speed (V) obtained from the engine speed after primary speed reduction by a gear transmission. The time period from the time of detection of a downshift operation to the time of completion of the reengagement of the clutch is composed of a first period until the clutch becomes a partially engaged condition after disengagement of the clutch, a second period during which the partially engaged condition is maintained, and a third period from the time when the clutch in the partially engaged condition starts to be driven in its engaging direction to the time when the reengagement of the clutch is completed.

Abstract: A crankcase of an internal combustion engine with a reduced size for an oil pan. A crankcase is composed of an upper crankcase half and a lower crankcase half. A wall portion for defining a space X as a flow passage for a lubricating oil is formed below a journal bolt mounting surface of the lower crankcase half. A tool insertion hole for insertion of a tool for tightening a journal bolt is formed through the wall portion.

Abstract: A clutch control assembly includes a clutch switches over a connected and disengaged state between an engine and a driven member. A first hydraulic pressure generating member is provided for generating hydraulic pressure for switching between a connected and disengaged state of the clutch according to an operation of a vehicle driver. A second hydraulic pressure generating member, independent from the first hydraulic pressure generating member, is provided for automatically generating hydraulic pressure for switching between a connected and disengaged state of the clutch according to drive conditions of the vehicle. A first piston with one side facing the first hydraulic pressure chamber linked to the first hydraulic pressure generating member and a second piston with one side facing the second hydraulic pressure chamber linked to the second hydraulic pressure generating member independent from the first hydraulic pressure generating member are interlock so as to be linked to the clutch.

Abstract: A clutch control device for obtaining a good shift shock reducing effect regardless of a change in clutch engagement point. A target NeV database stores a target NeV map as a target value of the ratio between an engine speed (Ne) and a vehicle speed (V) obtained from the engine speed after primary speed reduction by a gear transmission. The time period from the time of detection of a downshift operation to the time of completion of the reengagement of the clutch is composed of a first period until the clutch becomes a partially engaged condition after disengagement of the clutch, a second period during which the partially engaged condition is maintained, and a third period from the time when the clutch in the partially engaged condition starts to be driven in its engaging direction to the time when the reengagement of the clutch is completed.

Abstract: An engine-mounted mechanical fuel pump for an internal combustion engine contributes to a stable operation of the engine, a reduction in the weight of the engine, and a reduction in the pump drive loss. The engine includes a cylinder head provided with intake ports and exhaust ports therein, and fuel injection valves for injecting fuel into the inside of a tubular intake air routing assembly connected to the intake ports. A fuel pump is provided on the rear side of a cylinder block and on the upper side of a crankcase, in an arrangement where the intake ports are formed to extend rearwardly and the exhaust ports are formed to extend forwardly from the cylinder head. In one embodiment, the fuel pump is provided on the front side of the cylinder block, where the intake ports are formed to extend forwardly and the exhaust ports are formed to extend rearwardly.

Abstract: An intake flow control apparatus for an internal combustion engine eases operation of an air flow regulator and permits use of a short intake passage, thus providing a high output. The intake flow control apparatus includes an air routing member having an intake passage formed therein, and an air flow regulator opposed to an upstream-side opening of the intake passage. The air flow regulator moves in an intake axis direction while being guided by a light-weight guide structure to control the amount of intake air supplied. The air flow regulator may include plural valve elements different in operation timing, in which a valve actuator successively actuates the plural valve elements in accordance with a throttle operation to control the amount of intake air. The apparatus also includes a vacuum moderating structure for reducing the effective strength of a vacuum applied to the air flow regulator.

Abstract: An intake flow control apparatus for an internal combustion engine eases operation of an air flow regulator and permits use of a short intake passage, thus providing a high output. The intake flow control apparatus includes an air routing member having an intake passage formed therein, and an air flow regulator opposed to an upstream-side opening of the intake passage. The air flow regulator moves in an intake axis direction while being guided by a light-weight guide structure to control the amount of intake air supplied. The air flow regulator may include plural valve elements different in operation timing, in which a valve actuator successively actuates the plural valve elements in accordance with a throttle operation to control the amount of intake air. The apparatus also includes a vacuum moderating structure for reducing the effective strength of a vacuum applied to the air flow regulator.