Abstract: A motorcycle frame including a base portion and a removable portion that both bear operating loads of the motorcycle. The removable portion and base portion are fastened together at a joint comprising a first end cap having a protrusion, a second end cap having a recess, and a fastener having a fastener axis and extending through the first and second end caps. The protrusion and the recess are characterized by angled walls oriented at an acute angle with respect to the fastener axis. The angled wall engagement of the end caps ensures that substantially all shear loads in the joint are born by the end caps and not by the fastener. The motorcycle footpeg position can be changed by replacing the removable portion with a second removable portion having footpeg mounting structure at a different location than the removable portion.

Abstract: A motorcycle frame including a base portion and a removable portion that both bear operating loads of the motorcycle. The removable portion and base portion are fastened together at a joint comprising a first end cap having a protrusion, a second end cap having a recess, and a fastener having a fastener axis and extending through the first and second end caps. The protrusion and the recess are characterized by angled walls oriented at an acute angle with respect to the fastener axis. The angled wall engagement of the end caps ensures that substantially all shear loads in the joint are born by the end caps and not by the fastener. The motorcycle footpeg position can be changed by replacing the removable portion with a second removable portion having footpeg mounting structure at a different location than the removable portion.

Abstract: A motorcycle engine includes a crankshaft rotating in response to the reciprocation of pistons in cylinder bores. The inertial effects of the reciprocating pistons cause vibrations in the engine. A pair of balancer shafts are provided on opposite sides of the crankshaft, and are driven by the crankshaft through a drive member, such as a chain or belt. The balancer shafts are supported for rotation by bearings in the left side of the engine's crankcase, and by bearings in bearing housings that are mounted to the left side of the engine's crankcase. Thus, the balancer shafts are substantially only supported for rotation by the left side of the crankcase.

Abstract: A rocker assembly includes a base member having opposite ends, a flange interconnected with each of the opposite ends, a pair of rocker arm support shafts supported by the flanges, and a rocker arm interconnected with each rocker arm support shaft for rotation with respect to the rocker arm support shaft about a longitudinal axis. The rocker assembly is housed in a rocker box housing, is removable from the rocker box housing, and is mounted directly on the cylinder head of a motorcycle. The rocker box housing includes a generally wedge-shaped cover and a generally wedge-shaped base to allow the cover to be removed from the base in a generally horizontal direction.

Abstract: A drive assembly for a motorcycle including an engine having an output shaft and a transmission having an input shaft parallel to the output shaft and coupled to the output shaft. The engine includes a crankcase having a first interface portion with a first non-horizontal mounting surface. The transmission includes a transmission case having a second interface portion with a second non-horizontal mounting surface arranged to engage the first non-horizontal mounting surface. The second interface portion of the transmission case includes at least one fluid passage for the flow of fluid to or from the engine.

Abstract: A drive assembly for a motorcycle including an engine having an output shaft and a transmission having an input shaft parallel to the output shaft and coupled to the output shaft. The engine includes a crankcase having a first interface portion with a first non-horizontal mounting surface. The transmission includes a transmission case having a second interface portion with a second non-horizontal mounting surface arranged to engage the first non-horizontal mounting surface. The second interface portion of the transmission case includes at least one fluid passage for the flow of fluid to or from the engine.

Abstract: Method and apparatus for damping the effects of cyclic engine speed variations on the splines of a driving hub and the mating splines of a shaft driven by the hub. A caliper-like retaining mechanism includes a retaining nut threadedly engaging the distal end of the shaft, which distal end is journaled through a splined bore of the driving hub. A shoulder washer is disposed about the shaft proximate the hub shoulder, which shoulder washer is secured to the shaft by the retaining nut. A disc spring urges the shoulder washer into frictional engagement with the hub, which disc spring is retained in a circular groove within the hub. A predetermined preload is exerted by the disc spring on the shoulder washer, which preload is sufficient to overcome the forces which tend to induce rattle between the splines of the shaft and the corresponding splines of the hub.