Abstract: A supercharger for a V-twin motorcycle engine comprised of a transmission portion and a blower portion is disclosed. A first embodiment includes a power take-off coupling having a drive gear rotationally engaged with a vertical drive shaft wherein the drive shaft is coupled to the blower's input drive via a pair of output drive ration selection gears. A second embodiment includes an alternative transmission structure wherein rotational transmission passes through a series of spur gears and a set of bevel gears. A set of quick-change gears to alter the gear ratio of the second embodiment is also disclosed.