Abstract: An exhaust system for a motorcycle engine including a header having an upstream end adjacent a combustion chamber of the engine and having a downstream end opposite the upstream end. The exhaust system includes a catalytic converter positioned downstream of the combustion chamber and configured to improve the emissions quality of exhaust gases discharged from the combustion chamber. The exhaust system further includes a perforated section at least partially defining an exhaust passageway, the perforated section disposed adjacent the downstream end of the header. A resonator chamber is in fluid communication with the perforated section. The resonator chamber is configured to allow expansion of the exhaust gases in the exhaust passageway through the perforated section.

Abstract: An exhaust system for a motorcycle engine including a header having an upstream end adjacent a combustion chamber of the engine and having a downstream end opposite the upstream end. The exhaust system includes a catalytic converter positioned downstream of the combustion chamber and configured to improve the emissions quality of exhaust gases discharged from the combustion chamber. The exhaust system further includes a perforated section at least partially defining an exhaust passageway, the perforated section disposed adjacent the downstream end of the header. A resonator chamber is in fluid communication with the perforated section. The resonator chamber is configured to allow expansion of the exhaust gases in the exhaust passageway through the perforated section.

Abstract: An exhaust system for a motorcycle engine includes a muffler assembly. The muffler assembly includes a downstream attenuation portion adapted to be positioned substantially rearward of the motorcycle engine and having a first height, an upstream portion adapted to be positioned substantially forward of the motorcycle engine and having a second height, and an intermediate attenuation portion between the upstream portion and the downstream attenuation portion. The intermediate attenuation portion is adapted to be positioned substantially below the motorcycle engine and has a third height less than half the first height. In some embodiments, a motorcycle is provided, in which the motorcycle engine is positioned substantially within a recess of the muffler assembly to a depth greater than the third height.

Abstract: An intake system for a motorcycle having an engine. The intake system includes an air box having a first opening for receiving intake air and a second opening for supplying the intake air from the air box to a throttle assembly of the engine. A filter element is disposed within the air box for separating debris from the intake air. A valve is disposed within the air box between the filter element and the second opening. The valve is movable to provide a variable restriction to intake air flow through the air box.

Abstract: An air filter assembly for a motorcycle includes a housing at least partially defining an air intake passageway. The housing includes an opening a curved surface adjacent to the opening. An air filter is formed to be substantially planar in an unrestrained condition and deformed against the curved surface to conform to the curved surface. A retention mechanism retains the air filter against the curved surface.

Abstract: An intake system for a motorcycle having an engine. The intake system includes an air box having a first opening for receiving intake air and a second opening for supplying the intake air from the air box to a throttle assembly of the engine. A filter element is disposed within the air box for separating debris from the intake air. A valve is disposed within the air box between the filter element and the second opening. The valve is movable to provide a variable restriction to intake air flow through the air box.

Abstract: The present invention, in one aspect, relates to a propeller shaft housing for being secured in the gear case bore and configured for being securely engaged to the gear case bore by threaded screws that pass through bosses in the housing and into threaded holes in the gear case. More specifically, in an exemplary embodiment, the propeller shaft housing includes at least two bosses having compound angle holes therethrough, and at least two threaded holes in the gear case are arranged to align with one of the respective holes through the bosses. Respective screws extend through the holes in the bosses of the propeller shaft housing and into threaded engagement with the threaded holes in the gear case. In the exemplary embodiment, one of the threaded holes in the gear case is adjacent a skeg, and one of the threaded holes is adjacent a strut.

Abstract: The present invention, in one aspect, relates to a propeller shaft housing for being secured in the gear case bore and configured for being securely engaged to the gear case bore by threaded screws that pass through bosses in the housing and into threaded holes in the gear case. More specifically, in an exemplary embodiment, the propeller shaft housing includes at least two bosses having compound angle holes therethrough, and at least two threaded holes in the gear case are arranged to align with one of the respective holes through the bosses. Respective screws extend through the holes in the bosses of the propeller shaft housing and into threaded engagement with the threaded holes in the gear case. In the exemplary embodiment, one of the threaded holes in the gear case is adjacent a skeg, and one of the threaded holes is adjacent a strut.

Abstract: Disclosed herein is a lower unit for a marine propulsion device, such as an outboard motor or a stern drive unit, which lower unit comprising a gear case including a torpedo having a fore and aft axis and including a forward portion, a central portion extending rearwardly from the forward portion and having a generally cylindrical configuration concentric with the axis and defined by a radius, and an aft portion extending rearwardly from the central portion and including a circumferentially extending cylindrical sub-portion which is concentric with the axis, and which is defined by the radius, and a circumferentially extending conical sub-portion which is concentric with the axis, which extends for a circumferential length of not more than 180.degree., and which is defined by radii which are greater than the radius and which gradually increase in the direction toward the aft end.

Abstract: A marine propulsion device comprising a housing including a side wall having therein a water inlet and having an outer surface which extends generally in the fore and aft direction and which includes a ramped portion having a forward end and sloping rearwardly and outwardly from the inlet, and a forwardly-facing portion partially defining the inlet and extending inwardly from the forward end of the ramped portion, a water inlet screen covering the inlet and including an inner surface which slopes rearwardly and outwardly and which engages the ramped surface portion of the housing, screws for securing the screen to the housing, and a propeller shaft rotatably supported by the housing.