Abstract: A motorcycle having a crankcase supporting a crankshaft of an engine, a driving force transmission device at an intermediate position between the crankshaft and a driving wheel to transmit rotational force from the crankshaft, and a swing arm that swingably supports the driving wheel, wherein the driving force transmission device includes a continuously variable transmission provided with an endless flexible member stretched between a drive pulley and a driven pulley, and a continuously variable transmission case covering the continuously variable transmission, and wherein the swing arm includes a pivot portion provided on one end side of the swing arm to be swingably attached to a vehicle body frame or the crankcase, and a driving wheel support portion provided on another end side of the swing arm to rotatably support the driving wheel.

Abstract: An engine unit of a motorcycle includes a crankshaft, a piston, and a swing member. The crankshaft is housed in a crankcase in a direction such that a rotational center line is parallel to a vehicle-width direction. The piston is disposed above the crankshaft and reciprocates in an approximately up-down direction. The swing member is disposed forward of the crankshaft and the piston, coupled to the crankshaft by a coupling member, and swings in an approximately front-rear direction synchronized with a rotation of the crankshaft.

Abstract: A motorcycle having a crankcase supporting a crankshaft of an engine, a driving force transmission device at an intermediate position between the crankshaft and a driving wheel to transmit rotational force from the crankshaft, and a swing arm that swingably supports the driving wheel, wherein the driving force transmission device includes a continuously variable transmission provided with an endless flexible member stretched between a drive pulley and a driven pulley, and a continuously variable transmission case covering the continuously variable transmission, and wherein the swing arm includes a pivot portion provided on one end side of the swing arm to be swingably attached to a vehicle body frame or the crankcase, and a driving wheel support portion provided on another end side of the swing arm to rotatably support the driving wheel.

Abstract: In a cam housing structure for a three-dimensional cam including: plural intake side supporting parts rotatably supporting an intake side camshaft from above; and plural exhaust side supporting parts rotatably supporting an exhaust side camshaft from above at an upper part of a cylinder head, any one of the supporting parts of the intake side supporting parts or the exhaust side supporting parts is coupled to two or more pieces of the other supporting parts via reinforcing members.

Abstract: An intake system for an internal combustion engine includes: a cylinder block in which a combustion chamber is formed; a cylinder head in which a plurality of intake ports to introduce the combustion air into the combustion chamber are formed; a cylinder head cover disposed on an upper side of the cylinder head; a cam position sensor that detects positions in an axial direction of a motor of a cam slide mechanism and an intake side cam, the motor being disposed on an upper side of the cylinder head cover and driving the intake side cam; and an air cleaner disposed on an upper side of the cylinder head cover, the motor, and the cam position sensor, and a concave portion deeper than the other portions is formed in a bottom wall portion of the air cleaner, and is disposed between the motor and the cam position sensor.

Abstract: There is provided a lubricating structure for an internal combustion engine which has a crankcase, a cylinder block, a cylinder head housing a valve driving device, and a cam housing provided on an upper portion of the cylinder head to support an intake-side camshaft and an exhaust-side camshaft, the lubricating structure including: a main oil passage formed in the cam housing; an oil passage formed in an outer wall upper portion of the cylinder head so as to communicate with the main oil passage; and a pipe connection portion formed so as to allow an external oil pipe to be connected to the oil passage from an outside.

Abstract: An intake system for an internal combustion engine includes: a cylinder block in which a combustion chamber is formed; a cylinder head in which a plurality of intake ports to introduce the combustion air into the combustion chamber are formed; a cylinder head cover disposed on an upper side of the cylinder head; a cam position sensor that detects positions in an axial direction of a motor of a cam slide mechanism and an intake side cam, the motor being disposed on an upper side of the cylinder head cover and driving the intake side cam; and an air cleaner disposed on an upper side of the cylinder head cover, the motor, and the cam position sensor, and a concave portion deeper than the other portions is formed in a bottom wall portion of the air cleaner, and is disposed between the motor and the cam position sensor.

Abstract: A first intake pipe has one end connected to a second side of the surge tank which faces a second cylinder bank, and a second intake pipe has one end connected to a first side of the surge tank which faces a first cylinder bank. Adjacent the intake pipe ends, the first and second intake pipes are inversely bent near the second and first cylinder banks respectively, and have middle portions crossing below the surge tank and have other ends connected to the first and second cylinder banks. The first and second intake pipes are arranged in an alternating position in the cylinder-row direction. First and second branch pipes have upper ends connected into the surge tank and lower ends connected to adjacent other ends of the first and second intake pipes. Variable intake elements are disposed at the upper ends of the branch pipes to open and close.

Abstract: A V-type engine having an intake system structure formed of a surge tank and intake pipes. The intake system structure is divided into upper and lower blocks by a horizontal dividing surface positioned below the surge tank. The upper block includes the surge tank, and first and second upper pipe parts of the intake pipes. The lower block includes first and second lower pipe parts of the intake pipes. First and second seal parts surround the intake passages on the dividing surface toward the upper block. First and second straight inner sealing surfaces are arranged at the portion where the seal parts extend inwardly of the engine banks. Only these straight inner sealing surfaces are positioned below the surge tank.

Abstract: An intake apparatus of a multi-cylinder internal combustion engine wherein intake ports communicating with cylinders located at opposite longitudinal ends of a cylinder head are arranged so as to be inclined in a direction toward the longitudinal center of the cylinder head to reduce the longitudinal length of an installing section of the cylinder head for the intake manifold.

Abstract: An installation structure for an oil control valve, wherein a timing chain transmitting rotation of a crankshaft of an engine to camshafts is arranged, and a chain cover is installed on the engine so as to cover the timing chain. A cooling fan rotated by the crankshaft is located forward of a front part of the chain cover 14. An oil control valve which supplies oil delivered from an oil pump to an oil pressure actuator of an oil pressure control unit is mounted to a front part of the chain cover within the rotational trace of the cooling fan.

Abstract: A fuel injector fixing structure for use with an in-cylinder injection type engine is improved to reduce the number of processing man-hours and the number of parts as well as the number of assembling man-hours. In detail, each fuel injector is inserted into an injector fixing hole of a cylinder head, followed by attaching an injector fixing bracket. Then, each connecting portion of a fuel delivery pipe is connected to a fuel inlet of each fuel injector, followed by inserting a common bolt through an fixing boss portion and an injector fixing bracket, and fixing these elements to a common boss portion of the cylinder head. In this way, each fuel injector and the fuel delivery pipe can be fixed in the cylinder head by virtue of a common bolt, thereby making it possible to reduce the number of processing man-hours and the number of parts as well as the number of assembling man-hours.

Abstract: A V-type engine having an intake system structure formed of a surge tank and intake pipes. The intake system structure is divided into upper and lower blocks by a horizontal dividing surface positioned below the surge tank. The upper block includes the surge tank, and first and second upper pipe parts of the intake pipes. The lower block includes first and second lower pipe parts of the intake pipes. First and second seal parts surround the intake passages on the dividing surface toward the upper block. First and second straight inner sealing surfaces are arranged at the portion where the seal parts extend inwardly of the engine banks. Only these straight inner sealing surfaces are positioned below the surge tank.

Abstract: An intake system having a surge tank extending in a cylinder-row direction above a space between first and second cylinder banks of a V-type engine. A first intake pipe has one end thereof connected to a second side of the surge tank which faces the second cylinder bank, and a second intake pipe has one end thereof connected to a first side of the surge tank which faces the first cylinder bank. The first and second intake pipes have the one ends thereof bent and turned in the vicinities of the second and first cylinder banks respectively, and have middle portions crossing below the surge tank and have the other ends thereof connected to the first and second cylinder banks. First and second branch pipes have one ends thereof connected into the surge tank and the other ends thereof connected to adjacent other ends of the first and second intake pipes. Variable intake elements are disposed at the one ends of the branch pipes to open and close the branch pipes.

Abstract: An intake apparatus of a multi-cylinder internal combustion engine wherein intake ports communicating with cylinders located at opposite longitudinal ends of a cylinder head are arranged so as to be inclined in a direction toward the longitudinal center of the cylinder head to reduce the longitudinal length of an installing section of the cylinder head for the intake manifold.

Abstract: A fuel injector fixing structure for use with an in-cylinder injection type engine is improved to reduce the number of processing man-hours and the number of parts as well as the number of assembling man-hours. In detail, each fuel injector is inserted into an injector fixing hole of a cylinder head, followed by attaching an injector fixing bracket. Then, each connecting portion of a fuel delivery pipe is connected to a fuel inlet of each fuel injector, followed by inserting a common bolt through an fixing boss portion and an injector fixing bracket, and fixing these elements to a common boss portion of the cylinder head. In this way, each fuel injector and the fuel delivery pipe can be fixed in the cylinder head by virtue of a common bolt, thereby making it possible to reduce the number of processing man-hours and the number of parts as well as the number of assembling man-hours.

Abstract: In a combustion internal engine in which a cylinder head 8 is connected to a cylinder block 1 with a bolt 5 coming rough the cylinder head 8, more than half of a screw portion C of the bolt to be screwed in the cylinder block 1 is located under the central portion X of the depth of a water jacket 4. Since this portion of the cylinder block 1 is high in rigidity compared with the upper portion of the cylinder block, a gasket 9 can be tightened evenly.

Abstract: An installation structure for an oil control valve, wherein a timing chain transmitting rotation of a crankshaft of an engine to camshafts is arranged, and a chain cover is installed on the engine so as to cover the timing chain. A cooling fan rotated by the crankshaft is located forward of a front part of the chain cover 14. An oil control valve which supplies oil delivered from an oil pump to an oil pressure actuator of an oil pressure control unit is mounted to a front part of the chain cover within the rotational trace of the cooling fan.

Abstract: An oil passage for an internal combustion engine having a timing chain entrained around a crank sprocket and a cam sprocket, the crank sprocket being mounted on a crankshaft of the engine, and the cam sprocket being positioned on a camshaft. A timing case is disposed on one side of the engine for enclosing the timing chain. The oil passage for supplying the engine oil to the actuator is connected at an upstream side thereof to a downstream side of an oil pump, while a downstream side of the oil passage is positioned inside the timing case and around the cam sprocket.

Abstract: A hydraulic control valve mounting structure in an engine wherein a chain cover is attached to both a cylinder block and a cylinder head so as to cover a timing chain which transmits the rotation of a crank shaft to both intake and exhaust cam shafts. An oil pump is driven by the crank shaft, and a hydraulic control valve which supplies oil discharged from the oil pump to a hydraulic-actuated device in a hydraulic controller is attached to the chain cover. The hydraulic control valve mounting structure is such that the hydraulic control valve is attached to an outer surface of the chain cover while being positioned so that an upper portion thereof is covered at least partially with a mount installing boss portion of the chain cover.