Abstract: The invention provides a motorcycle having a frame, an engine coupled to the frame, and a crankshaft assembly. The crankshaft assembly includes a first flywheel half having an aperture, a crank pin including a first end portion, a second end portion opposite the first end portion, and a bearing surface between the first and second end portions. The first end portion is press-fit into the aperture of the first flywheel half. The first end portion, the second end portion, and the bearing surface are coated with a friction enhancer. A bearing is positioned at least partially onto the bearing surface, and a connecting rod has an aperture that at least partially receives the bearing.

Abstract: The invention provides a motorcycle having a frame, an engine coupled to the frame, and a crankshaft assembly. The crankshaft assembly includes a first flywheel half having an aperture, a crank pin including a first end portion, a second end portion opposite the first end portion, and a bearing surface between the first and second end portions. The first end portion is press-fit into the aperture of the first flywheel half. The first end portion, the second end portion, and the bearing surface are coated with a fiction enhancer. A bearing is positioned at least partially onto the bearing surface, and a connecting rod has an aperture that at least partially receives the bearing.

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: An internal combustion engine has a valve guide that is pressed into an opening in the cylinder head. An exhaust valve is slidably mounted in the bore of the valve guide. The exhaust valve has a head which is sized to cover the exhaust port, a stem which is slidably mounted in the valve guide so that the stem moves axially within the bore of the guide to open and close the valve head over the exhaust port, and a shank which extends between the valve stem and the valve head. The valve stem includes a recessed portion adjacent the valve shank. Except for the recessed portion, the valve stem is coated with a solid lubricant coating which is not capable of surviving repeated exposure to the hot exhaust gas passing through the exhaust port. The valve stem including the recessed portion remains located within the internal bore of the valve guide whenever the valve is opened or closed in such a manner that the recessed portion does not contact the bore of the valve guide.

Abstract: A low-friction, extended-life exhaust valve has a coating on the valve stem that is protected from hot exhaust gases. The valve stem slides axially in a valve guide pressed into the cylinder head, and the coating on the valve stem is receded away from the end of the valve guide exposed to the hot exhaust gases passing through the exhaust port. Protecting the coating from the hot exhaust gases allows the use of coatings that cannot normally withstand the harsh environment to which the exhaust valve is exposed. The preferred coating is a molybdenum oxide coating, which not only retains lubricating oil because of its porous nature, but also has solid lubricity which is useful in case of hydrostatic breakdown of the lubricant between engine cycles.

Abstract: An improved crankcase pressure regulation system for an internal combustion engine has a floating-disk type vacuum pressure regulator operatively connected to a breather tube for blowby gases upstream of a flow restriction such as an oil separator. The breather tube has an inlet that receives crankcase blowby gases from a breather port in the crankcase and an outlet that feeds blowby gases into an air intake housing where the blowby gases are mixed with filtered engine intake air. The blowby gases are recirculated into the engine for combustion. The floating-disk type vacuum regulator has an air filter to filter ambient air that is added to the blowby gases and later recirculated into the engine air intake for combustion.