Abstract: A torque fluctuation absorber includes a first outer helical spline, an intermediate member, an outer member, a first spring, and a second spring. The first outer helical spline is rotatable integrally with a torque transmission shaft. The intermediate member is able to move in a first axial direction and in a second axial direction. The intermediate member is linked with the torque transmission shaft through a first helical spline coupling including the first outer helical spline. Axial movement of the outer member with respect to the torque transmission shaft is regulated. The outer member is linked with the intermediate member through a second helical spline coupling. The first spring biases the intermediate member in the first axial direction. The second spring biases the intermediate member in the second axial direction.

Abstract: An engine is provided to facilitate installation of a compressor on an engine. The engine can include a crankshaft, a front end, and an installation structure, and can be disposed in an engine compartment having an opening for accessing the engine. The installation structure can comprise an installation mount that can be disposed at the front end of the engine. The installation mount can extend substantially parallel to the crankshaft of the engine. The installation mount can include a surface configured for mounting the compressor. Further, the installation mount can be configured with the surface thereof facing toward the opening of the engine compartment. Additionally, the installation structure can be configured to facilitate meshing engagement of the crankshaft with a drive shaft of the compressor.

Abstract: A boat includes a connection structure that connects couplings via a transfer shaft on a rear end portion of a crankshaft extending rearward from an engine. The crankshaft and the transfer shaft are connected by screwing an external thread and a front internal thread, and the transfer shaft and the couplings are connected by screwing an external thread and an internal thread. There are provided an inner bolt that strengthens the connection between the external thread and the front internal thread, an end bolt that strengthens the connection between the transfer shaft and the couplings, and an outer nut that strengthens the connection between the crankshaft and the transfer shaft. The boat can prevent movement between the crankshaft and an intermediate member and between the intermediate member and a coupling both in a rotational direction and in an axial direction without causing an increase of processing time or processing cost.

Abstract: A boat includes a connection structure that connects couplings via a transfer shaft on a rear end portion of a crankshaft extending rearward from an engine. The crankshaft and the transfer shaft are connected by screwing an external thread and a front internal thread, and the transfer shaft and the couplings are connected by screwing an external thread and an internal thread. There are provided an inner bolt that strengthens the connection between the external thread and the front internal thread, an end bolt that strengthens the connection between the transfer shaft and the couplings, and an outer nut that strengthens the connection between the crankshaft and the transfer shaft. The boat can prevent movement between the crankshaft and an intermediate member and between the intermediate member and a coupling both in a rotational direction and in an axial direction without causing an increase of processing time or processing cost.

Abstract: An air passage and a cooling water passage can be formed in an intercooler provided on a small planing boat. A cooling water inlet of a cooling water passage in the intercooler can be provided at the lower end of the intercooler. A cooling water outlet can be at the upper end of the intercooler. The intercooler can be vertically elongated and disposed at the front side of the engine. Further, a discharge port of a supercharger can be directed upwardly and an air inlet of the intercooler can be provided on the intercooler at the upper part. Furthermore, the intercooler, the supercharger and an intake manifold can be arranged such that when viewed in the lateral direction, the intercooler and supercharger overlap each other and when viewed in the longitudinal direction, the intercooler and intake manifold can also overlap each other. Moreover, the intercooler can be of a two-pass type.

Abstract: An engine is provided to facilitate installation of a compressor on an engine. The engine can include a crankshaft, a front end, and an installation structure, and can be disposed in an engine compartment having an opening for accessing the engine. The installation structure can comprise an installation mount that can be disposed at the front end of the engine. The installation mount can extend generally normal to the crankshaft of the engine. The installation mount can include a surface configured for mounting the compressor. Further, the installation mount can be configured with the surface thereof facing toward the opening of the engine compartment. Additionally, the installation structure can be configured to facilitate meshing engagement of the crankshaft with a drive shaft of the compressor.

Abstract: An air passage and a cooling water passage can be formed in an intercooler provided on a small planing boat. A cooling water inlet of a cooling water passage in the intercooler can be provided at the lower end of the intercooler. A cooling water outlet can be at the upper end of the intercooler. The intercooler can be vertically elongated and disposed at the front side of the engine. Further, a discharge port of a supercharger can be directed upwardly and an air inlet of the intercooler can be provided on the intercooler at the upper part. Furthermore, the intercooler, the supercharger and an intake manifold can be arranged such that when viewed in the lateral direction, the intercooler and supercharger overlap each other and when viewed in the longitudinal direction, the intercooler and intake manifold can also overlap each other. Moreover, the intercooler can be of a two-pass type.

Abstract: A watercraft includes an engine output control device that can adjust the maximum output of the engine. The output device can be constructed of mechanical devices for adjusting the relationship between the movement of a throttle lever and a throttle valve, an electronic device for proportionally controlling the position of throttle valves in relation to the movement of the throttle lever, are other devices for controlling engine speeds in other ways.

Abstract: A watercraft includes an improved engine control system that enhances the responsiveness of the watercraft and eases watercraft operation. The watercraft includes a propulsion device, such as a jet propulsion unit, and an engine that powers the propulsion device. The engine control system is configured to maintain or increase engine speed under certain operating conditions.

Abstract: A watercraft includes an improved engine control system that enhances the responsiveness of the watercraft and eases watercraft operation. The watercraft includes a propulsion device, such as a jet propulsion unit, and an engine that powers the propulsion device. The engine control system is configured to maintain or increase engine speed under certain operating conditions.

Abstract: A watercraft includes an engine output control device that can adjust the maximum output of the engine. The output device can be constructed of mechanical devices for adjusting the relationship between the movement of a throttle lever and a throttle valve, an electronic device for proportionally controlling the position of throttle valves in relation to the movement of the throttle lever, are other devices for controlling engine speeds in other ways.

Abstract: A watercraft includes a performance mode selector which enables a rider to select normal operation of the watercraft or an economy mode operation. In the economy mode operation, the watercraft either disables cylinders or reduces fuel injection and ignition in order to limit the maximum engine speed obtained by the engine when the throttle lever is fully depressed Additionally, the watercraft can disable cylinders or selectively reduce fuel injection or ignition when an abnormal operating parameter has been detected.

Abstract: An internal combustion engine includes an exhaust system. Additionally, the engine includes a secondary air injection system that injects air into the exhaust system to burn un-burnt fuel that may be entrained in the exhaust gases. The secondary air injection system can include individual secondary injection conduits, each having a check valve, and being configured to inject air into each exhaust runner of the engine. The secondary air injection system can also include, in lieu or in addition, a cooling jacket cooling a portion of the exhaust system between upstream from a catalyst device and downstream from the point of injection of secondary air.

Abstract: A watercraft includes an improved engine control system that enhances the responsiveness of the watercraft and eases watercraft operation. The watercraft includes a propulsion device, such as a jet propulsion unit, and an engine that powers the propulsion device. The engine control system is configured to maintain or increase engine speed under certain operating conditions.

Abstract: An engine for a watercraft has an exhaust system having an exhaust pipe and an expansion chamber. The exhaust pipe has a plurality of runners corresponding to the number of cylinders in the engine. The runners extend upward to a merge point and then longitudinally in a generally forward direction. The exhaust pipe wraps around a front surface of the cylinder block and connects to an exhaust chamber. The exhaust pipe and exhaust chamber protect sensitive engine components, such as spark plugs and an exhaust control valve and actuating system from sloshing water. In addition, the exhaust system extends the length of the runners and enhances side-to-side balancing of the engine.

Abstract: An exhaust control for an internal combustion engine powering a watercraft is disclosed. The exhaust control includes an exhaust manifold connected to the engine and having a passage therethrough leading from an exhaust passage extending from a combustion chamber within the engine. An exhaust pipe, preferably in the form of an expansion pipe, extends from the exhaust manifold for leading the exhaust to a discharge. The exhaust pipe is connected to the engine, preferably with a number of brackets. A catalyst is positioned within the portion of the exhaust pipe which is connected to the engine. In a preferred arrangement the manifold extends towards the front end of the engine and the expansion pipe extends therefrom towards the rear of the engine through a valley formed by the engine and an induction system thereof.

Abstract: An exhaust system is provided for an engine of the type used to power a watercraft. The engine has at least one combustion chamber with an exhaust passage leading therefrom. A crankshaft of the engine rotates about an axis passing through the engine. The exhaust system includes an exhaust manifold connected to the engine and having a passage leading therethrough from the exhaust passage leading from the combustion chamber. The exhaust manifold is connected to an exhaust pipe leading to an exhaust discharge. The connection of the exhaust manifold and exhaust pipe is generally aligned with the crankshaft axis, but positioned vertically thereabove.

Abstract: A small watercraft includes an improved exhaust system that reduces the width of the engine and associated exhaust pipes. The watercraft includes a hull having a length in a longitudinal direction, a width in a lateral direction, and a longitudinal center line. A multi-cylinder engine is carried by the hull. The engine includes an exhaust system with multiple exhaust inlet ends and at least one downstream end. The exhaust inlet ends communicate with the respective cylinders of the engine. A flow axis through each inlet end extends in a direction generally parallel to the longitudinal axis of the hull. As a result, the exhaust system does not significantly protrude in a lateral direction beyond the sides of the engine. The hull consequently has a smaller width than the prior watercrafts which improves it maneuverability.

Abstract: An exhaust control for an internal combustion engine powering a watercraft is disclosed. The exhaust control includes a valve which is movably mounted with respect to the engine and having a portion for extension into an exhaust passage thereof. Preferably, the valve is of the sliding type. A motor is connected to the hull of the watercraft near a maintenance opening in the top of the watercraft. In one embodiment, a pulley is mounted to the output shaft of the motor and to a shaft which is movably connected to the valve, and a looping cable extends around the pulleys. In a second embodiment, a cable has its first end connected to the output shaft of the motor and its second end connected to the valve, and a spring engages the valve, biasing it in one direction.

Abstract: A small personal watercraft having an exhaust system that is designed to provide adequate length and which has a downwardly inclined section that is disposed above the exhaust manifold for ensuring that water cannot enter the engine through the exhaust system. The engine is water cooled and the coolant that is circulated through the engine cooling jacket is discharged back to the body of water in which the watercraft is operating through the exhaust system. A direct coolant discharge having a relatively large effective area for limiting the amount of water entering the exhaust system. A tell-tale discharge is disposed in a lower portion of the hull to be visible by a rider but will not enter the passenger's area and will drain from the tell-tale when the engine is not running.