Abstract: A method and device for increasing the amount of fuel to an engine during acceleration is provided. A secondary source of fuel in addition to a first source of fuel is introduced into the engine during acceleration. The secondary source of fuel is introduced through a secondary fuel delivery line which is opened by a valve actuated in response to throttle control movement. In a first embodiment, the secondary fuel delivery line communicates with a fuel delivery area from which fuel is supplied to the first fuel source. The valve is pressed open by the throttle control along with a primary fuel source needle valve control, allowing fuel from the fuel delivery area to flow through the second fuel line in addition to the first fuel source. In second and third embodiments, the secondary fuel line communicates with an excess fuel return line. A valve extends across the fuel return line and secondary fuel line.

Abstract: The present invention is an exhaust system for an engine powering a water propulsion device of a watercraft having a hull with a front end and a rear end. The water propulsion device is positioned near the rear end of the watercraft, with the engine connected to the hull and positioned generally towards the front end of the watercraft from the water propulsion device and having an output shaft arranged to drive the water propulsion device. The engine has a fuel supply system including a fuel tank positioned towards the front end of the watercraft from the engine and generally at an end of the engine opposite the water propulsion device, the engine having an exhaust system defining an exhaust flow path from the engine towards the front end of the watercraft along a first side of the fuel tank and then along a second side of the fuel tank towards the rear of said watercraft to an exhaust discharge.

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 propulsion system for a watercraft includes an upwardly inclined drive shaft to improve acceleration. The upwardly inclined orientation of the impeller shaft, and thus a similar orientation of the discharge stream exiting the jet propulsion system, causes the bow of the watercraft to ride out of the water when the watercraft is planing. The watercraft thus has less surface contact with the water, and travels faster.

Abstract: A lubricating system for a four-cycle engine positioned within an engine compartment of a personal watercraft for powering a water propulsion unit thereof, is disclosed. The engine compartment, and engine therein, is accessible through a maintenance opening in deck of the watercraft. Preferably, the lubricating system includes an oil filter which is positioned at other than the bottom of the engine for access through the maintenance opening, such as at the front or rear end of the engine. In addition, the engine preferably includes an oil drain which is positioned below the oil filter for draining the oil from the engine.

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: In accordance with the present invention there is provided a cooling system for a four-cycle engine utilized to power a water propulsion device of a watercraft of the type including a propulsion passage having an inlet in the bottom of the hull and an outlet at the stern of the watercraft. In a first embodiment, coolant is delivered from the propulsion passage to an exhaust manifold cooling jacket, then to at least one passage extending through the engine and then an exhaust pipe cooling jacket. As an additional aspect of the invention, coolant is provided to an oil cooler for cooling lubricating oil used to lubricate the engine. In another embodiment of the present invention, an exhaust cooling system is provided for the four-cycle engine powering the watercraft, separate from the cooling system for the cylinder block and cylinder head of the engine. Coolant is supplied through cooling jackets provided along substantially the length of the exhaust system from the engine to a discharge from the watercraft.

Abstract: Two embodiments of two-cycle V-type crankcase compression internal combustion engines for powering a jet propelled watercraft. In each embodiment, the pistons of the cylinder banks each drive their own crankshafts which are geared by a transmission to an output shaft. The exhaust system for the engine is disposed on the outside of the cylinder banks and includes an expansion chamber and a portion of the exhaust system that passes over the engine. The induction system for the engine is positioned in the valley between the cylinder banks.

Abstract: A lubricating system for a four-cycle engine positioned within an engine compartment of a personal watercraft for powering a water propulsion unit thereof, is disclosed. The engine compartment, and engine therein, is accessible through a maintenance opening in deck of the watercraft. Preferably, the lubricating system includes an oil filter which is positioned at other than the bottom of the engine for access through the maintenance opening, such as at the front or rear end of the engine. In addition, the engine preferably includes an oil drain which is positioned below the oil filter for draining the oil from the engine.

Abstract: A number of embodiments of jet propulsion systems for watercraft that employ twin impellers contained within a common housing assembly at the end of a common inlet duct having a single water inlet opening that can be positioned centrally of the watercraft to avoid drawing air in during abrupt maneuvering. By using twin impellers, the use of straightening vanes can be substantially eliminated. In addition, a small dividing wall extends from the area forwardly of the impellers only into the water inlet ducts sufficiently so as to reduce counter-effects of swirling from between the two impellers and without requiring any substantial change in direction of the water flow from the water inlet opening to the impellers.

Abstract: A two-cycle internal combustion engine for a watercraft that includes a cylinder block having a cylinder bore, a piston reciprocating in the cylinder bore and an exhaust port formed in the cylinder block. An exhaust path extends from the cylinder bore for exhausting combustion products from the cylinder bore. An exhaust control valve cooperates with the exhaust port and is movable between at least a first position for advancing the closing of the exhaust port so as to increase the compression ratio in the engine and a second position for delaying the closing of the exhaust port so as to decrease the compression ratio in the engine. Means for controlling the exhaust control valve between the first and second position are provided and are controlled in response to a watercraft condition.

Abstract: A method and device for increasing the amount of fuel to an engine during acceleration is provided. A secondary source of fuel in addition to a first source of fuel is introduced into the engine during acceleration. The secondary source of fuel is introduced through a secondary fuel delivery line which is opened by a valve actuated in response to throttle control movement. In a first embodiment, the secondary fuel delivery line communicates with a fuel delivery area from which fuel is supplied to the first fuel source. The valve is pressed open by the throttle control along with a primary fuel source needle valve control, allowing fuel from the fuel delivery area to flow through the second fuel line in addition to the first fuel source. In second and third embodiments, the secondary fuel line communicates with an excess fuel return line. A valve extends across the fuel return line and secondary fuel line.

Abstract: A trim adjusting system for a small jet propelled personal watercraft. The trim is adjusted automatically in response to sensed water conditions which will indicate, among other things, the condition of the water flowing through the water inlet opening of the jet propulsion unit. The measured conditions may include water condition, watercraft speed and watercraft trim angle. The arrangement also permits manual operation and the permissible range of trim adjustment is less in manual operation than in automatic operation.

Abstract: A personal watercraft having a compact engine arrangement for driving a propulsion device such as a jet pump positioned to the rear of and on the underside of the watercraft. The engine is disposed so that its cylinder block is at an angle to a vertical plane, with the exhaust manifold being positioned on the underside of the cylinder bank. An expansion chamber device is provided at the rear end of the engine and at a height that is higher than the exhaust ports of the engine and the discharge of the exhaust system so as to provide a trap for precluding flow of water to the engine through the exhaust system. This positioning of the engine places its crankshaft in offset relationship to the drive shaft of the propulsion device, and a two-stage step-down transmission drives the drive shaft from the crankshaft.

Abstract: A number of embodiments of engine induction system configurations for adapting four-cycle, multi-cylinder engines for use in small, personal watercraft. This is accomplished by canting the engine at an angle to a vertically extending plane and positioning the induction system on the upper portion of the cylinder head. Various configurations of manifold and carburetor locations are disclosed so as to achieve this purpose.

Abstract: A jet propulsion unit for a watercraft that employs a pair of counter rotating impellers that are disposed immediately adjacent each other so that the need for straightening vanes is eliminated. The impellers are driven by a bevel gear transmission to rotate in opposite directions, which bevel gear transmission is contained within the jet propulsion unit outer housing but forwardly of the flow path of water therethrough. This bevel gear transmission is driven by a single input shaft through a flexible coupling.

Abstract: A small, personal watercraft powered by a four cycle internal combustion engine. The engine is provided with a dry sump lubrication system for permitting the engine to be mounted low in the hull and this dry sump lubrication system includes a lubricant tank mounted within the hull separately from, but spaced closely to, the engine. Induction and exhaust systems are provided for the engine which include position responsive valves that close when the watercraft is inverted to preclude water from entering the combustion chamber through either the intake or the exhaust system. The induction system also includes an air inlet device that has its own position responsive check valve and which provides a centrifugal separator for separating water from the air inducted into the engine.

Abstract: A jet propelled watercraft having an outboard motor type of jet propulsion unit. The jet propulsion unit is disposed in substantial part forwardly of the transom and beneath the undersurface of the hull for improving its pumping efficiency. The jet propulsion unit is driven by a transmission including a drive shaft having a pivotal joint. The jet propulsion unit is pivotal relative to the engine about an axis containing the axis of the universal joint so that the water inlet opening may be swung upwardly through an opening in the undersurface of the hull which is above the water level for clearing foreign objects from the jet propulsion unit water inlet opening.

Abstract: An improved steering control for a jet propelled watercraft wherein the steering control is provided by at least a pair of pivotally connected nozzle sections with the upstream nozzle section being pivoted first and the downstream nozzle section being pivoted second so as to permit a larger range of deviation in the discharge flow without obstructing the discharge nozzle of the jet propulsion unit. Both mechanical and hydraulic control systems are disclosed.

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.