Abstract: An intake air control system of a V-type internal combustion engine having cylinder axes formed in a V-shape with a crankshaft provided therebetween is provided. An operation input shaft driven by an operator's input and an operation input shaft turning angle sensor that detects a turning angle of the operation input shaft are also provided. A throttle body having a throttle valve is formed with an intake passage for each of the cylinders. The operation input shaft is located between valve shafts of an opposing pair of throttle valves that are located on opposing bank portions of the V-type internal combustion engine, when viewed from the direction of the crankshaft. The operation input shaft is disposed separately from the throttle valve shafts and the operation input shaft turning angle sensor is provided at a shaft end of the operation input shaft.

Abstract: An inexpensive fuel supply device having a high output is achieved using low-output fuel pumps. First and second pumps, which are two inexpensive pumps having a low output, are disposed on a common mounting seat an inlet of each of the fuel pumps approaches a common fuel filter, discharge ports are connected to a common discharge passage so that the amount of fuel corresponding to the sum of the amounts of discharged fuel of the fuel pumps can be supplied from the common discharge passage, a common pressure regulator is connected to the common discharge passage, and the entire structure is formed as a unit, thereby obtaining an inexpensive pump unit having a high output.

Abstract: An internal combustion engine includes a cylinder head having a plurality of intake ports; throttle devices including a plurality of respective intake passages equipped with throttle valves therein; a plurality of fuel injection valves for injecting fuel into the corresponding intake passages; a fuel pipe adapted to supply fuel to the fuel injection valves; and a pulsation damper connected to the fuel pipe to damp fuel pressure pulsation. In the engine, a connection pipe coupled to the pulsation damper is formed between a plurality of branch portions with respect a longitudinal direction of the fuel pipe, adapted to deliver fuel from the fuel pipe to the fuel injection valves and the connection pipe is disposed to at least partially overlap the fuel injection valve as viewed from the longitudinal direction of the fuel pipe.

Abstract: A coolant air bleed structure is provided for a water-cooled internal combustion engine having a plurality of cylinders and a cylinder head, formed at upper portion of the cylinders. The cylinder head includes a coolant jacket formed therein. The coolant air bleed structure is disposed in an air bleed hole formed in a protrusion formed at a substantially central vertical portion of a sidewall of the cylinder head. The coolant air bleed structure is operatively connected to the coolant jacket, and includes a jiggle valve which is configured to open during a coolant changing operation.

Abstract: An intake air control system of a V-type internal combustion engine having cylinder axes formed in a V-shape with a crankshaft provided therebetween is provided. An operation input shaft driven by an operator's input and an operation input shaft turning angle sensor that detects a turning angle of the operation input shaft are also provided. A throttle body having a throttle valve is formed with an intake passage for each of the cylinders. The operation input shaft is located between valve shafts of an opposing pair of throttle valves that are located on opposing bank portions of the V-type internal combustion engine, when viewed from the direction of the crankshaft. The operation input shaft is disposed separately from the throttle valve shafts and the operation input shaft turning angle sensor is provided at a shaft end of the operation input shaft.

Abstract: An internal combustion engine includes a cylinder head having a plurality of intake ports; throttle devices including a plurality of respective intake passages equipped with throttle valves therein; a plurality of fuel injection valves for injecting fuel into the corresponding intake passages; a fuel pipe adapted to supply fuel to the fuel injection valves; and a pulsation damper connected to the fuel pipe to damp fuel pressure pulsation. In the engine, a connection pipe coupled to the pulsation damper is formed between a plurality of branch portions with respect a longitudinal direction of the fuel pipe, adapted to deliver fuel from the fuel pipe to the fuel injection valves and the connection pipe is disposed to at least partially overlap the fuel injection valve as viewed from the longitudinal direction of the fuel pipe.

Abstract: In an exhaust system for a motorcycle in which an engine main body of a multi-cylinder engine has an oil pan on a lower portion thereof, and is mounted on a vehicle body with a plurality of expansion chambers being connected to a downstream side of an assembled portion of a plurality of exhaust pipes that extend out of the respective cylinders of the engine main body, respectively. The muffler includes a first expansion chamber that is connected to the assembled portion and the other expansion chambers that are the assembled portion are disposed on one side of the oil pan. The first continuous to the first expansion chamber. The respective exhaust pipes and expansion chamber is disposed on the other side of the oil pan with the other expansion chambers being disposed to the rear of the engine main body.

Abstract: A coolant air bleed structure is provided for a water-cooled internal combustion engine having a plurality of cylinders and a cylinder head, formed at upper portion of the cylinders. The cylinder head includes a coolant jacket formed therein. The coolant air bleed structure is disposed in an air bleed hole formed in a protrusion formed at a substantially central vertical portion of a sidewall of the cylinder head. The coolant air bleed structure is operatively connected to the coolant jacket, and includes a jiggle valve which is configured to open during a coolant changing operation.

Abstract: In an exhaust system for a motorcycle in which an engine main body of a multi-cylinder engine has an oil pan on a lower portion thereof, and is mounted on a vehicle body with a plurality of expansion chambers being connected to a downstream side of an assembled portion of a plurality of exhaust pipes that extend out of the respective cylinders of the engine main body, respectively. The muffler includes a first expansion chamber that is connected to the assembled portion and the other expansion chambers that are continuous to the first expansion chamber. The respective exhaust pipes and the assembled portion are disposed on one side of the oil pan. The first expansion chamber is disposed on the other side of the oil pan with the other expansion chambers being disposed to the rear of the engine main body.