| A motorcycle engine is an engine found in a | | | | Twin design as used on the Triumph |
| motorcycle, which serves to propel the | | | | Bonneville. BMW makes their famous flat-twin |
| motorcycle. The motor typically sits | | | | ("boxer twin")engine where the cylinders are |
| immediately under the fuel tank, in between | | | | horizontally opposed, protruding from either |
| and just forward of the rider's legs. | | | | side of the frame. The boxer is one of two |
| | | | twin-cylinder arrangement that is inherently |
| Types of Engine | | | | balanced, producing very low vibration levels |
| | | | without the use of counterbalance shafts. The |
| Four Stroke Engine Engine | | | | 90-degree Vee, like Ducati and Moto Guzzi |
| configurationAlmost all commercially | | | | use, has perfectly counterbalancing primary |
| available motorcycles are driven by | | | | forces and minor secondary imbalances acting |
| conventional gasoline internal combustion | | | | in a plane perpendicular to the centerline of |
| engines, but some small scooter-type models | | | | the Vee as viewed from the side. That also |
| use an electric motor. | | | | produces very low vibration levels. Narrow |
| | | | angle V twins vibrate. [1] Sunbeam produced a |
| Gasoline engines can be compared by many | | | | water cooled inline twin driving a propshaft. |
| criteria. | | | | |
| | | | Narrow-angle V-twin engines dominate the |
| Displacement | | | | cruiser motorcycle segment. |
| | | | |
| Displacement is defined as the total volume | | | | Three cylinders |
| of air/fuel mixture an engine can draw in | | | | |
| during one complete engine cycle. In a piston | | | | Three-cylinder designs are unusual — |
| engine, this is the volume that is swept as | | | | they are referred to as "triples" and are |
| the pistons are moved from top dead center to | | | | normally inline triples in layout. The |
| bottom dead center. To the layperson this is | | | | British Hinkley built Triumph and Italian |
| the "size" of the engine. Motorcycle engines | | | | Benelli are two of the motorcycle |
| range from 50 cc (cubic centimetres) to 2300 | | | | manufactures using triples in their large |
| cc. | | | | displacement motorcycles. |
| | | | |
| Number of cylinders | | | | On the other hand, in a two-stroke world |
| | | | triples were more common. In the 70's |
| Motorcycles have mostly, but not exclusively, | | | | Kawasaki had its 250, 350 500 and 750 triples |
| been produced with one to four cylinders, and | | | | which were known for their power (but maybe |
| designers have tried every imaginable layout. | | | | not rideability) and Suzuki had 380, 550 and |
| Engines with more cylinders provide more | | | | 750 triples of which the last one was water |
| power for the same displacement, and feel | | | | cooled and thus gained the nick name "Water |
| smoother to ride. Engines with fewer | | | | Buffalo". All the others above were air |
| cylinders are cheaper, lighter and easier to | | | | cooled. |
| maintain. | | | | |
| | | | Four cylinders |
| Single cylinder | | | | |
| | | | Four-cylinder engines are colloquially known |
| One-cylinder motorcycles are known as | | | | as "four-bangers." They are quite similar to |
| "singles," and "thumpers" (for the sound they | | | | car engines, and most commonly have a |
| make). In most singles, the cylinder points | | | | transverse-mounted inline four layout, |
| up and slightly forward, spark plug on top. | | | | although some are longitudinal (as in the |
| They are most common in off-road and | | | | earlier BMW K series). V-4 and boxer designs |
| dual-purpose motorcycles, though there are | | | | (as in the Honda Gold Wing series) have been |
| some cruisers and small-displacement | | | | produced. One of the more unusal designs was |
| sport-bikes that use single-cylinder engines. | | | | the Ariel Square Four, effectively two |
| | | | parallel-twin engines one in front of the |
| Two cylinders | | | | other in a common crankcase - it had |
| | | | remarkably little vibration. |
| Two-cylinder motorcycles are called "twins." | | | | |
| The two most common arrangements are the | | | | Since the advent of Honda's CB750 |
| "V-twin" where the cylinders form a "V" | | | | straight-four engine, straight-fours have |
| around the crankshaft, which is oriented | | | | dominated the non-cruiser street motorcycle |
| transversely (i.e., perpendicular to the | | | | segments. |
| direction of travel). | | | | |
| | | | Five cylinders |
| also common especially in classic British | | | | |
| motorcyles and Japanese motorcycles, is the | | | | Honda has produced a five-cylinder engine for |
| inline twin also known as the parallel twin. | | | | racing, the RCV, but no five-cylinders exist |
| In this design the cylinders are side by side | | | | for commercial production motorcycles. |
| vertically above the crankcase. If not | | | | |
| vertical they are generally close to in order | | | | Six cylinders |
| to maximise airflow cooling. | | | | |
| | | | Six cylinder engines are uncommon, and found |
| The angle in the V-twins varies from around | | | | only on the biggest motorcycles. One of the |
| 45 degrees to 90 degrees. Typical of the | | | | best six cylinder examples is the Kawasaki |
| former is the Harley-Davidson and Vincent | | | | Z1300. Nowadays the most famous six cylinder |
| engines which due to their firing order tend | | | | engine is the boxer used on the Honda |
| to vibrate more. Ducati and Moto Guzzi make | | | | Valkyrie series and Honda Gold Wing. |
| V-twins cylinders at s 90 degree angles to | | | | |
| quell primary vibrations. Moto guzzi | | | | More than six cylinders |
| motorcyles have had their engines crosswise | | | | |
| in the frame one cylinder to the left, one to | | | | A number of custom and one-off motorcycles |
| the right. | | | | use more than six cylinders. For example, the |
| | | | Boss Hoss motorcycle uses a Chevy V-8 motor. |
| The parallel twin engine configuration was | | | | But no major motorcycle manufaturer uses more |
| made famous by Edward Turners Triumph Speed | | | | than six cylinders. |