A V-twin motorcycle engine typically has two pistons. The "V" in V-twin refers to the arrangement of the cylinders, which are positioned in a V shape. Each cylinder in a V-twin engine contains a piston that moves up and down within the cylinder as part of the combustion process. Therefore, a V-twin engine has two pistons, with each piston located in its respective cylinder. This configuration is commonly found in many motorcycle models and is known for providing good power and torque characteristics.