Natural Air Cooling: The strips like extensions (fins) are integrated on the outside of the cylinder and cylinder block. These fins are designed in such a way that they can transfer maximum heat. The fins remain in direct contact with atmospheric air. The air blows over the fins and carries away the heat. When the vehicle travels, the relative speed of air increases, hence the rate of heat removed also increases. In motorcycles and scooters and in several small size engines, natural air cooling is preferred due to its simplicity.