"True V-twin" vs V-2

There is some ambiguity regarding what defines a V-twin which arose from 180 degree "V" engines (see Flat engine). When the cylinders are arranged in a V pattern, it is generally accepted as being a V engine. However, some people differentiate using "V-twin" to mean the classic V design of a shared crank pin for each pair of cylinders and "V-2" to indicate a boxer-style crank with a separate crank pin for each cylinder. This convention is not common, and applies only to two cylinder engines. For example, while most V8 engines use shared crank pins for cylinder pairs, they are not referred to as "V-octuplets". Most engine manufacturers do not use this convention and the 1983 Honda Shadow 750 is known as being the first V-twin with an offset-dual-pin crankshaft.

V angles

Generally, any two-cylinder motorcycle engine with its two cylinders at an equidistant opposite angles from the center rotation of the crankshaft is referred to as a V-twin. The V-twin engine is not designated by a specific angle, but people associate the 45° Harley-Davidson engine with the classic V-twin configuration. While any motorcycle can have a v-twin engine, cruiser style motorcycles most commonly use this configuration. For example, Honda offers a 52° engine in several of their cruiser motorcycles. But other angles can be seen such as the 75° Suzuki and KTM, the 80° Honda CX-500, the 47° Vincent, and the 60° Aprilia. The engine manufacturer S&S offers a 45° and a 56.25° engine for use in custom choppers.

A 90° twin engine, such as the signature Ducati engine and recent Aprilia engines — with the front cylinder approximately parallel to the ground and the rear cylinder vertical — is generally referred to as a L-twin engine. There is no technical distinction between V-twin and L-Twin engines. These are merely names used by convention. From an engineering perspective, the 90° angle is preferred as it acts as a counterweight to balance the engine.