Abstract: An outboard motor includes a housing unit mounted on an associated watercraft. An engine is disposed above the housing unit. The engine defines a first exhaust passage communicating with a combustion chamber of the engine. The housing unit defines a second exhaust passage communicating with the first exhaust passage. The second exhaust passage communicates with outside through at least an underwater exhaust discharge port formed at a portion of the housing unit. An air intake device communicates with either the first exhaust passage or the second exhaust passage. The air intake device includes a one-way valve that allows air to enter the first or second exhaust passage and inhibits exhaust gases from moving beyond the one-way valve.

Abstract: An outboard motor includes a housing unit mounted on an associated watercraft. An engine is disposed above the housing unit. The engine defines a first exhaust passage communicating with a combustion chamber of the engine. The housing unit defines a second exhaust passage communicating with the first exhaust passage. The second exhaust passage communicates with outside through at least an underwater exhaust discharge port formed at a portion of the housing unit. An air intake device communicates with either the first exhaust passage or the second exhaust passage. The air intake device includes a one-way valve that allows air to enter the first or second exhaust passage and inhibits exhaust gases from moving beyond the one-way valve.

Abstract: An engine throttle valve linkage includes an improved construction that can be placed in a space around an engine in an internal cavity of a protective cowling so as to control throttle valves under a synchronized condition. In a preferred mode, the engine includes first and second air intake conduits communicating with combustion chambers in the respective cylinder banks of the V-shaped engine and extending generally along side surfaces of the engine body. The first and second intake conduits have first and second throttle valves, respectively, both regulating an amount of air flowing through the respective intake conduits. A manipulator actuates both the first and second throttle valves. The manipulator includes a pair of manipulating members coupled with the first and second throttle valves. The manipulator is disposed generally between the first and second air intake conduits so as to be positioned on the engine body.

Abstract: A lubricant filler structure for an internal combustion engine includes a lubricant filler tube having a lower end connected to the crankcase and an upper end forming a filling port. The filler tube is disposed forwardly at an angle with respect to the vertical. The engine also has a cover member through which the lubricant filler structure extends. The cover member and the lubricant filler structure are configured to enhance accessibility of a lubricant filling port by the user.

Abstract: An outboard motor features a v-type internal combustion engine having a generally vertically extending crankshaft. Exhaust gases from combustion chambers are routed through a set of exhaust manifolds positioned within the valley defined by the two banks of cylinders. The exhaust flow is merged within a passage formed in the cylinder block prior to passing the exhaust flow into a passage formed within an exhaust guide plate to which the engine is mounted. The merged flow passage is positioned to allow a compact outboard motor construction. The motor also features a cooling pattern by which the exhaust manifold runners, the exhaust manifold, the cylinder head, the valley and the cylinders are cooled in that order.

Abstract: An outboard motor has various electrical components mounted on a front side of the crankcase chamber. The crankcase chamber is connected by an electrical line to a negative terminal of a battery in an associated watercraft in order to ground the crankcase chamber. Thus, the electrical components are easily grounded by being connected to the crankcase chamber. An intake silencer of the engine induction system is positioned adjacent the crankcase chamber and at least one of the electrical components is disposed between the silencer and the crankcase member. An oil filter mount is also disposed on the front side of the crankcase chamber. The mount is adapted so that the oil filter can be installed thereon and is tilted along an inclined axis.

Abstract: An engine has a valve drive arrangement that uses dead space within an outboard motor cowling. The engine has a first set of cylinders and a second set of cylinders. The first set of cylinders is offset from the second set of cylinders such that one is arranged closer to a first end of the engine that the other. The higher set of cylinders includes a set of cam shafts that are coupled at the end closer to the first end of the engine while the lower set of cylinders includes a set of cam shafts that are coupled at the end farther from the first end of the engine. A drive arrangement connects the two sets of cam shafts to the crankshaft.

Abstract: An outboard motor features a v-type internal combustion engine having a generally vertically extending crankshaft. Exhaust gases from combustion chambers are routed through a set of exhaust manifolds positioned within the valley defined by the two banks of cylinders. The exhaust flow is merged within a passage formed in the cylinder block prior to passing the exhaust flow into a passage formed within an exhaust guide plate to which the engine is mounted. The merged flow passage is positioned to allow a compact outboard motor construction. The motor also features a cooling pattern by which the exhaust manifold runners, the exhaust manifold, the cylinder head, the valley and the cylinders are cooled in that order.

Abstract: A lubricant filler structure for an internal combustion engine includes a lubricant filler tube having a lower end connected to the crankcase and an upper end forming a filling port. The filler tube is disposed forwardly at an angle with respect to the vertical. The engine also has a cover member through which the lubricant filler structure extends. The cover member and the lubricant filler structure are configured to enhance accessibility of a lubricant filling port by the user.

Abstract: An engine includes an improved induction system which reduces the girth of the engine, simplifies assembly, and improves better power output balance between the cylinders of the engine. The illustrated engine is a multi-cylinder engine and is designed to power an outboard motor; hence, the cylinders of the engine are arranged above one another. Thus, the engine comprises at least first and second combustion chambers. The induction system selectively communicates with the combustion chambers to supply a fuel/air charge thereto. The induction system includes a first intake passage leading to the first combustion chamber and having a first fuel injector communicating therewith, and a second intake passage leading to the second combustion chamber and having a second fuel injector communicating therewith.

Abstract: An outboard motor features a v-type internal combustion engine having a generally vertically extending crankshaft. Exhaust gases from combustion chambers are routed through a set of exhaust manifolds positioned within the valley defined by the two banks of cylinders. The exhaust flow is merged within a passage formed in the cylinder block prior to passing the exhaust flow into a passage formed within an exhaust guide plate to which the engine is mounted. The merged flow passage is positioned to allow a compact outboard motor construction. The motor also features a cooling pattern by which the exhaust manifold runners, the exhaust manifold, the cylinder head, the valley and the cylinders are cooled in that order.

Abstract: An outboard motor includes an internal combustion engine having an induction system formed of a pair of vertically extending plenum chambers which communicate with the combustion chambers formed in the engine via a plurality of intake runners. A common throttle device is located upstream from the plenum chambers and communicates with the plenum chambers via an induction passage having an branch portion. The throttle device is arranged at least partially below an upper surface of the crankcase of the engine. Thus, the overall height of the engine is reduced, thereby reducing the overall height of an outer cowling member provided over the engine.

Abstract: An exhaust system for an outboard motor wherein the exhaust pipe which depends into the expansion chamber formed in the drive shaft housing is provided with a separate cooling jacket. Water from this separate cooling jacket is discharged into the expansion chamber at a point well below the discharge end of the exhaust pipe in a direction away from the exhaust pipe so as to avoid water ingestion into the engine through the exhaust system. A second expansion chamber communicates with an above the water exhaust gas discharge. This second expansion chamber communicates with the first expansion chamber through a restricted path formed in part by a flange of the exhaust pipe.

Abstract: An ignition arrangement for an internal combustion engine having an output shaft supported for rotation about an axis. The engine includes an engine housing at least partially enclosing the output shaft. Oil seals at least partially surround the output shaft for sealing the output shaft to the engine housing. An oil seal housing at least partially surrounds the output shaft and at least partially engages the oil seals. The oil seal housing directly supports a first ignition component.

Abstract: An outboard motor exhaust system and control for insuring good running and effective exhaust gas silencing and treatment. The system includes a very compact exhaust system that includes an expansion chamber formed beneath the exhaust guide plate and to which the exhaust gases are delivered and removed at optimal locations. Furthermore, a feedback control employing a combustion condition sensor is employed along with a catalyst in the exhaust. Sensors are provided upstream and downstream of the catalyst to ensure that it is operating at optimum conditions.

Abstract: A number of embodiments of an exhaust system for outboard motors that includes a trap portion in a conduit which conveys the exhaust gases from an expansion chamber formed in the drive shaft housing to an underwater exhaust gas discharge. The trap portion has a horizontal section that is disposed above the water level, and various orientations are depicted. In addition, a catalyst is also provided, and the catalyst is protected from water also by the construction.