VTwin

A V-twin, or V-twin engine, is a two-cylinder internal combustion engine with the cylinders arranged in a V around a common crankshaft. It is widely used in motorcycles and also appears in light industrial, marine, and stationary applications. The banks typically meet at angles from about 45 to 90 degrees. The arrangement yields a compact footprint and strong low- to mid-range torque, which is desirable for cruising motorcycles.

Each cylinder has its own combustion chamber and valve-train, but they share the crankshaft. The firing interval depends on the crank design and the V angle; at 45 degrees the cylinders fire irregularly, producing a distinctive exhaust note. V-twins can be air- or liquid-cooled and may use pushrods or overhead cams. The narrow bank angle can simplify frame design, but may complicate cooling and maintenance of the heads.

Advantages include high torque at low revs and a compact form; disadvantages include vibration, especially in air-cooled designs, and sometimes a broader engine width that affects handling. Modern engineering uses counterweights, balanced crankpins, and improved lubrication to mitigate these issues.

Historically, V-twins emerged in the late 19th and early 20th centuries, with several manufacturers developing variants. Harley-Davidson popularized the 45-degree V-twin in American motorcycles, shaping the layout's cultural image. Ducati has used a 90-degree V-twin (often called an L-twin) in its designs, illustrating angle variation within the class.

Today V-twins remain common in motorcycles, especially cruisers and touring bikes, and are also used in some marine and power-equipment applications. Variants include air-, oil-, and water-cooled configurations, with different valve-train arrangements and lubrication systems.