Abstract: A personal watercraft can have a steering nozzle pivoting in accordance with the operation of a steering handle unit to change the traveling direction of a vehicle body. A steering position sensor can be configured to detect the steering angle of the steering handle unit. An actuator can be arranged to pivot the steering nozzle to change the steered angle thereof. A running speed sensor can be configured to detect the running speed of the vehicle body, and a control device. The control device can determine an operational amount of the actuator and control the actuator based upon the detection amount of the steering position sensor, the running speed sensor, and a steering ratio preset with reference to the steering angle and the running speed. The steering ratio is set to be smaller as the running speed becomes larger.

Abstract: A personal watercraft can have a steering nozzle pivoting in accordance with the operation of a steering handle unit to change the traveling direction of a vehicle body. A steering position sensor can be configured to detect the steering angle of the steering handle unit. An actuator can be arranged to pivot the steering nozzle to change the steered angle thereof. A running speed sensor can be configured to detect the running speed of the vehicle body, and a control device. The control device can determine an operational amount of the actuator and control the actuator based upon the detection amount of the steering position sensor, the running speed sensor, and a steering ratio preset with reference to the steering angle and the running speed. The steering ratio is set to be smaller as the running speed becomes larger.

Abstract: A small watercraft with an emergency shut-off system is provided. The emergency shut-off system is configured to shut off the engine of the small watercraft when the small watercraft is overturned. The emergency shut-off system comprises an electronic control unit that is operatively coupled to an overturn sensor and the engine. The electronic control unit is configured to sense a signal generated by the overturn switch. The electronic control unit is also configured to determine if the signal generated by the overturn switch continues for a period longer than a preset amount of time and to shut off the engine if the signal generated by the overturn switch continues beyond the preset amount of time.

Abstract: A small watercraft with an emergency shut-off system is provided. The emergency shut-off system is configured to shut off the engine of the small watercraft when the small watercraft is overturned. The emergency shut-off system comprises an electronic control unit that is operatively coupled to an overturn sensor and the engine. The electronic control unit is configured to sense a signal generated by the overturn switch. The electronic control unit is also configured to determine if the signal generated by the overturn switch continues for a period longer than a preset amount of time and to shut off the engine if the signal generated by the overturn switch continues beyond the preset amount of time. The electronic control unit can also be configured to activate a bilge pump when a level of water within the watercraft exceeds a predetermined level.

Abstract: A small watercraft with an emergency shut-off system is provided. The emergency shut-off system is configured to shut off the engine of the small watercraft when the small watercraft is overturned. The emergency shut-off system comprises an electronic control unit that is operatively coupled to an overturn sensor and the engine. The electronic control unit is configured to sense a signal generated by the overturn switch. The electronic control unit is also configured to determine if the signal generated by the overturn switch continues for a period longer than a preset amount of time and to shut off the engine if the signal generated by the overturn switch continues beyond the preset amount of time.

Abstract: A diagnostic system is provided to aid a technician or engineer in diagnosing an internal combustion engine. The diagnostic system comprises an electronic control unit that is operatively coupled to a data storage device and to one or more engine sensors. The electronic control unit is configured to collect data from the one or more engine sensors and to store that data in the data storage device. A computer is selectively coupled to the data storage device. The computer program is configured to display specific sets of data stored in the data storage device in various formats.

Abstract: A small watercraft with an emergency shut-off system is provided. The emergency shut-off system is configured to shut off the engine of the small watercraft when the small watercraft is overturned. The emergency shut-off system comprises an electronic control unit that is operatively coupled to an overturn sensor and the engine. The electronic control unit is configured to sense a signal generated by the overturn switch. The electronic control unit is also configured to determine if the signal generated by the overturn switch continues for a period longer than a preset amount of time and to shut off the engine if the signal generated by the overturn switch continues beyond the preset amount of time. The electronic control unit can also be configured to activate a bilge pump when a level of water within the watercraft exceeds a predetermined level.

Abstract: A small watercraft hull defines a vertically oriented, central longitudinal plane of the watercraft. The hull has an engine compartment with an internal combustion engine disposed therein. The engine has an engine body comprising a crankcase, a cylinder block and a cylinder head and includes at least one cylinder bore defining a cylinder axis. An air induction system is provided to guide air into a combustion chamber of the engine. The air induction system includes a plenum chamber. An exhaust system is also provided for guiding exhaust gases from the combustion chamber to the atmosphere. The exhaust system includes an exhaust conduit. The cylinder axis is canted with respect to the central plane and the exhaust conduit is disposed substantially on a side of the central plane to which the cylinder axis is canted.

Abstract: A small planing watercraft including a hull, a propulsion unit mounted on the hull and a high RPM-high output engine for driving the propulsion unit, wherein the engine includes at least one intake valve and an intake valve timing control system for advancing the opening and closing of the intake valve when the watercraft is operating below a predetermined speed corresponding to a velocity at which the watercraft transitions from non-planing to planing motion. The engine may also include a long air intake passage for low-speed operation and a short air intake passage for high-speed operation, with an air intake control valve in the short air intake passage that is closed when the watercraft is operating below the predetermined speed. The engine may also include an exhaust control valve for constricting the exhaust passage, and a system for at least partially closing the exhaust control valve when the watercraft is operating below the predetermined speed.

Abstract: An engine for a watercraft has a coupling plate interposed between a cylinder block and an exhaust manifold. The coupling plate comprises exhaust passages that complement the shapes of cylinder exhaust discharge ports and the exhaust manifold inlet ports. The coupling plate also includes a water jacket for use with a water cooling system. The cooling system can receive coolant from a pressure chamber within a jet pump unit of the watercraft. The cooling system also can include a lubricant cooler that receives coolant from an engine cooling jacket, an exhaust system cooling jacket or another cooling jacket.

Abstract: A small watercraft includes an internal combustion engine having an air induction system that minimizes the volume of water delivered to the combustion chambers and maintains a generally low center of gravity. The induction system includes an intake silencer which is divided into an upstream chamber and a downstream chamber. The chambers communicate with each other through a passageway. The upstream chamber has an inlet for drawing air from the engine compartment, and the downstream chamber has an outlet communicating through a conduit with an intake chamber. The inlet and outlet are positioned in an upper portion of the silencer and the passageway is positioned in a lower portion of the silencer. Thus, air flowing through the silencer must change direction and water in the air will be separated from the air flow and deposited on the inner walls of the silencer. Each of the upstream and downstream chambers has a drain port through which water may be evacuated.

Abstract: A watercraft having a water propulsion unit driven by an impeller shaft which is powered by a four-cycle internal combustion engine is disclosed. The engine has a crankshaft which drives, via a transmission, the impeller shaft. The transmission is arranged so that the crankshaft of the engine does not contact lubricant in a lubricant reservoir of a lubricating system of the engine. In a first arrangement, the four-cycle engine includes an oil reservoir positioned at a lower portion of the engine. In this arrangement, a crankshaft of the engine extends along an axis above an axis along which the impeller shaft rotates, where the crankshaft and impeller shaft are in driving relation via a gear-type transmission. In a second arrangement, the engine is provided with a dry-sump type lubricating system with an oil reservoir positioned remote of the bottom of the engine, such as on the hull.

Abstract: A lubrication cooling system for an internal combustion engine positioned within an engine compartment of a personal watercraft for powering a water propulsion unit thereof, is disclosed. The lubrication cooling system lowers the temperature of the lubrication for the internal combustion engine of a personal watercraft. Preferably, the lubrication cooling system incorporates cooling the lubrication by introducing the lubrication cooler to a fluid such as forced air or ambient water.

Abstract: A small watercraft with an emergency shut-off system is provided. The emergency shut-off system is configured to shut off the engine of the small watercraft when the small watercraft is overturned. The emergency shut-off system comprises an electronic control unit that is operatively coupled to an overturn sensor and the engine. The electronic control unit is configured to sense a signal generated by the overturn switch. The electronic control unit is also configured to determine if the signal generated by the overturn switch continues for a period longer than a preset amount of time and to shut off the engine if the signal generated by the overturn switch continues beyond the preset amount of time.

Abstract: A small watercraft hull defines a vertically oriented, central longitudinal plane of the watercraft. The hull has an engine compartment with an internal combustion engine disposed therein. The engine has an engine body comprising a crankcase, a cylinder block and a cylinder head and includes at least one cylinder bore defining a cylinder axis. An air induction system is provided to guide air into a combustion chamber of the engine. The air induction system includes a plenum chamber. An exhaust system is also provided for guiding exhaust gases from the combustion chamber to the atmosphere. The exhaust system includes an exhaust conduit. The cylinder axis is canted with respect to the central plane and the exhaust conduit is disposed substantially on a side of the central plane to which the cylinder axis is canted.

Abstract: A small watercraft includes a lubrication system having at least one pump, a lubricant reservoir, and a lubricant filter. The lubricant pump is configured to circulate lubricant between the reservoir, the filter and the engine. The lubricant filter is arranged either on a forward side or a rearward side of the lubricant reservoir. Alternatively, the lubricant filter may be mounted on a side of the engine opposite the lubricant reservoir and on a forward side or rearward side of the exhaust manifold. Further, the lubricant pump and the lubricant reservoir may be mounted rearward from a rear end of the engine body. Each of the arrangements provide an engine having a compactly arranged lubrication system which minimizes the affect on the overall width of the engine caused by the lubrication system.

Abstract: A personal watercraft features a hull defining an engine compartment. An engine is mounted within the engine compartment. The engine comprises a cylinder head, a cylinder body and a crankcase. An induction system supplies air to the engine for combustion. The induction system comprising an intake box, an intake silencer, and a set of intake pipes that extend from the intake box to the engine. The intake pipes extend upward and inward toward the engine. A protective chamber is formed by an inside surface of the intake box, an outside surface of the engine and a lower surface of the pipes. A vapor separator is disposed within this protective chamber. The protective chamber can be augmented by an overhanging portion of the cylinder head, a protrusion from the cylinder body or other extensions from the intake box.

Abstract: A hull for a watercraft has a longitudinal axis generally extending from fore to aft of the watercraft. The hull includes a seat pedestal forming at least two side walls supporting a seat. The side walls generally extend longitudinally relative to the hull. The seat pedestal defines an engine compartment in which an engine is placed. Each side wall defines a maintenance opening communicating with the engine compartment. The openings are elongated along the longitudinal axis. Normally, caps close the respective openings. Each cap has a bulged out configuration to form an inner recessed area therein. A portion of an exhaust conduit extends beyond the opening to occupy one of the recessed areas. In one arrangement, an air induction system includes a plenum chamber unit that has a portion disposed close to the opening. The portion of the plenum chamber unit also defines another opening thereon.

Abstract: An improved fuel delivery and injection system for a small watercraft engine reduces the heat effects within an enclosed engine compartment upon various components of the engine and upon the fuel within the fuel system. The fuel system integrates a fuel pump within a fuel tank at a location which minimizes the effects of watercraft leaning. The inlet of the fuel pump desirably corresponds, in the lateral direction, with a position of an inlet to the jet pump unit. In this position, the pump is less likely to draw air as the watercraft maneuvers. The fuel lines also are arranged within the engine to minimize the effect of engine heat produced by the exhaust system on the fuel delivery lines. The arrangement of the fuel pump and fuel delivery lines consequently improves the consistency of the fuel/air ratio within the fuel charge produced by the engine as less air and vapor delivered to the fuel injectors.

Abstract: An exhaust cleaning system for a marine propulsion engine that includes a catalyst positioned within a tube that communicates with an expansion chamber. A cooling jacket extends around at least a portion of the exhaust system and the liquid coolant is discharged into the exhaust system for flow with the exhaust gases. A number of different arrangements are shown for precluding the coolant from flowing back into the exhaust system and contacting the catalyst bed either when the watercraft is inverted and righted or in the event the engine is stopped and restarted.