Abstract: An exhaust system for a marine propulsion outboard drive wherein the exhaust gases are normally discharged to the atmosphere at a point below the level of the body of water in which the watercraft is operating. A catalyst bed is provided in the exhaust system and the catalyst bed is protected from damage by pumping water from the exhaust conduit in response to certain conditions. These conditions may be either rapid deceleration of the engine or watercraft, stopping of the engine, or any of a combination of sensed factors. The water is pumped by a water pump which is positioned either in the outboard drive or in the hull of the associated watercraft. The pumping of water is initiated for only a predetermined time or until the sensed condition no longer is existent.

Abstract: Two embodiments of outboard motors embodying tuned exhaust systems having exhaust pipes and expansion chambers into which the exhaust pipes extend. A catalyst is positioned in the exhaust system downstream of the point where the exhaust pipe terminates in the expansion chamber so as to preclude interference with the exhaust tuning. The catalyst bed is removable for ease of servicing without necessitating removal of the outboard motor from the its attachment to the associated watercraft and a trap device is provided for precluding water from entering the engine through its exhaust ports.

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.

Abstract: A number of embodiments of outboard motors having catalytic exhaust systems. In each embodiment, an expansion chamber is formed in the drive shaft housing and the exhaust gases are delivered to the expansion chamber from an exhaust pipe that extends at least in part through the expansion chamber and which terminates at its lower end in the lower portion of the expansion chamber. A catalyst bed is positioned at the upper end of the expansion chamber and beneath the engine and through which the exhaust gases must pass for discharge through a further exhaust conduit which extends at least in part through the expansion chamber and which terminates at an underwater exhaust gas discharge.

Abstract: An exhaust gas purifying arrangement is provided for an outboard motor for a watercraft. At least one exhaust port is provided which opens into a first exhaust passage having a first catalyst member lining at least a portion of its inner wall. The first exhaust passage then opens into an exhaust expansion chamber. Next, a second exhaust passage originates just beyond the expansion chamber. A second catalyst member is mounted within and across a section of exhaust passage beyond the first exhaust passage and at a location above the water line within which the outboard motor operates. A first passageway is provided which leads from the second exhaust passage, from a position beyond the second catalyst member, to an exhaust outlet located at a position below a body of water in which the watercraft operates.

Abstract: An exhaust gas purifying arrangement is provided for an outboard motor for a watercraft. At least one exhaust port is provided which opens into a first exhaust passage having a first catalyst member lining at least a portion of its inner wall. The first exhaust passage then opens into an exhaust expansion chamber. Next, a second exhaust passage originates just beyond the expansion chamber. A second catalyst member is mounted within and across a section of exhaust passage beyond the first exhaust passage and at a location above the water line within which the outboard motor operates. A first passageway is provided which leads from the second exhaust passage, from a position beyond the second catalyst member, to an exhaust outlet located at a position below a body of water in which the watercraft operates.

Abstract: An outboard motor having an improved timing plate mounting arrangement for its ignition system. The mounting plate has a hub portion that is journaled on the outer side of a cylindrical extension of the crankshaft wall and is held in place by a retainer plate that is bolted to the end surface of the wall and radially inwardly of the hub portion. The ignition plate carries a pulser coil that extends on the outer periphery of the flywheel of the engine and charging coils are mounted internally of the flywheel on the retainer plate.

Abstract: Two embodiments of power head constructions for outboard motors wherein a liquid supply system for the internal combustion engine of the power head is contained within its protective cowling. This liquid supply system includes first and second spaced liquid tanks that are interconnected by a conduit for flow therebetween.

Abstract: An improved steering device for a marine propulsion unit that incorporates a steering bracket that is clamped to the transom of the associated watercraft in proximity to the tilt axis of the outboard drive. A steering rod is reciprocally supported in a bore in the steering bracket and is connected at one end to a push pull cable and at the other end to the steering arm of the outboard drive for effecting its steering.