Save space, strong power, good heat dissipation effect and low oil consumption. An engine is a machine that can convert other forms of energy into mechanical energy. Common engines are internal combustion engine (reciprocating piston engine) and external combustion engine (Stirling engine, steam engine, etc.). ), jet engines, motors, etc. For example, internal combustion engines usually convert chemical energy into mechanical energy. Engine is not only suitable for power generation device, but also refers to the whole machine (such as gasoline engine and aero-engine) including power device. The engine was first born in Britain, so the concept of engine also originated in English. Its original meaning refers to "a mechanical device that generates power". If the displacement of parallel double cylinders is affected. If the displacement is too large, the cylinder will be large, and the juxtaposition will be too prominent. V-cylinder can slim down to the maximum, which is most suitable for the narrow space of motorcycle. Harley-Davidson's motorcycle always has a displacement of two liters. How wide the engine would be if there were two parallel cylinders. In addition, the V-shaped cylinder can be air-cooled, but if two cylinders are juxtaposed, it must be water-cooled. Think about how many accessories are added to the water cooling. Mainly saves space and has better heat dissipation performance. Advantages and disadvantages of V-cylinder engine: 1.v cylinder can reduce the height of the engine, so it can be made into a torsion engine with small cylinder diameter and large stroke; 2.v-shaped cylinder can reduce the width and reduce the influence of motorcycle width on maneuverability; 3. The V cylinder has the same problem of unbalanced ignition angle as the asynchronous double cylinder (much better than asynchronous); 4. The V-shaped cylinder assembly is complex and difficult to maintain.