A crankshaft assembly for a motorcycle includes a first flywheel half with a polygonal-shaped aperture therein and a second flywheel half with a polygonal-shaped aperture therein. The first and second flywheel halves are interconnected by press-fitting opposing first and second polygonal shaped end portions of a crank pin into respective polygonal-shaped apertures of the first and second flywheel half. A bearing is positioned at least partially on a surface of a cylindrical central portion of the crank pin and a connecting rod has an aperture at least partially receiving the bearing.

A crankshaft having an axis of rotation is disclosed. The crankshaft includes a main throw having a web, a main pin extending from the web that is coaxial with the axis of rotation and an aperture in the web. The crankshaft also includes a crank throw having a web, a crank pin extending from the web, a central aperture positioned in the web that is coaxial with the axis of rotation. The crank pin is positioned in the aperture of the main throw and a connecting rod is positioned on the crank pin. The crankshaft includes various features for distribution of oil to components.