List of motorcycles by type of engine is a list of motorcycles by the type of motorcycle engine used by the vehicle, such as by the number of cylinders or configuration. A transverse engine is an engine mounted in a vehicle so that the engine's crankshaft axis is perpendicular to the direction of travel. In a longitudinal engine configuration, the engine's crankshaft axis is parallel with the direction of travel. However, the description of the orientation of "V" and "flat" motorcycle engines differs from this convention. Motorcycles with a V-twin engine mounted with its crankshaft mounted in line with the frame, e.g. the Honda CX series, are said to have "transverse" engines, while motorcycles with a V-twin mounted with its crankshaft mounted perpendicular to the frame, e.g. most Harley-D