Motorcycle engine
[3] Using frames based both on the earlier boneshaker and the later—and in many ways completely modern—safety bicycle design, these early steam motorcycles experimented with a variety of engine placement strategies, as well as transmission and options.
The origins of the scooter engine arrangement (including the shaft drive) can be traced back to the 19th century but the current layout became generally adopted after the Great War.
[4][5] The steam cycles were also simply neglected and forgotten by many historians, even as the Michaux-Perreaux waited forty years[verification needed] on display in the National Motor Museum, Beaulieu.
[verification needed][6] In recent years, a surge in interest in clean energy has put many new electric powered two wheelers on the market, and they are registered as motorcycles or scooters, without the type of powerplant being an issue.
Diesel motorcycles were also experimented with briefly in the 20th century, and are again the subject of interest due to fuel economy and the needs of military logistics.
[7] The overwhelming majority of the motorcycles produced and used in the world today have small displacement air-cooled single-cylinder engines, both two- and four-strokes.
Some motorcycles such as Harley-Davidsons, Moto Guzzis and BMWs become identifiable by their cylinder-head types, namely airhead, panhead, oilhead, and even knucklehead.
In the early 1960s, BSA introduced new short-stroke unit construction 500 and 650 cc parallel twins to replace their existing pre-unit long-stroke engines.
The decision by Lucas to discontinue making dynamos and magnetos, and to produce only alternators and coil ignition systems, was a significant factor in forcing the redesign.
[12] The majority of motorcycle engines are configured as singles, parallel twins, triples, fours and sixes; and all these may be inline or transverse.
Until the mid-1960s, road-racing machines, like the UK's Matchless, AJS and Norton, tended to be large singles, but since then multicylinder racers have become the norm.
The simplicity of these engines, often relying on a single carburetor, make them relatively easy to maintain and repair in remote locations with few tools.
Starting with Edward Turner's 1937 Triumph Speed Twin design, and until the mid-1970s, the parallel-twin was the most common British motorcycle type.
A Vee-angle of 90°, as used by Ducati and Moto Guzzi, can give perfect primary and secondary balance, with a pleasingly irregular firing order.
V-twins may be mounted either longitudinally with the cylinders protruding either side, like the Honda CX500 and Moto Guzzi, or transversely, such as Harley-Davidson, Ducati, or Aprilia.
The boxer has perfect primary balance, and only a small rocking couple, and unlike a V-twin, regular firing intervals, producing very low vibration levels, without the use of counterbalance shafts.
The British Hinckley Triumph factory has specialized in transverse triples, although their 2,300 cc Rocket III has its engine mounted longitudinally.
One of the more unusual designs was the Ariel Square Four, effectively two parallel-twin engines one in front of the other in a common crankcase — it had remarkably little vibration due to the contra-rotating crankshafts.
The FN had its engine in line with the frame; this layout would be copied by manufacturers in Europe and the United States before World War II.
[14] In the United States, inline fours made by Henderson and Indian were bought by enthusiasts and by police departments, the latter using them as pursuit motorcycles.
The configuration results in inherently good balance of the reciprocating parts, a low centre of gravity, and a very short engine length.
Australian company Drysdale have built short runs of 750 cc V8 superbikes and 1L V8 roadgoing motorcycles, both with engines specifically developed for the purpose.
The improved fuel efficiency is offset by the increased weight, reduced acceleration and potential difficulty of starting, at least in colder climates.
Products BV Holland announced their first diesel-powered motorcycle, its Track T-800CDI, using an 800 cc three-cylinder Daimler Chrysler diesel engine.
[24] Several armies are moving to an all-diesel engine fleet to reduce the fire risks of gasoline and the need to provide two different fuels.
The cooling effect of this fan is enough to prevent the engine overheating in most conditions, so liquid-cooled bikes are safe to use in a city, where traffic may frequently be at a standstill.
Some models, mostly scooters, are equipped with fans that force the air to go past the cylinder block, which solves the problem of city driving.
Fuel injection and computer engine management systems are now normal on middle range and larger motorcycles and are increasingly being incorporated onto the smaller machines, partly driven by better emission control and lower maintenance but mostly by manufacturing cost considerations.
Most sports bikes now use a ram-air induction system where as road speed increases, more air is forced through ducts in the fairing to pressurize the airbox.
[26] Not to be confused with the original Ram-Air system where an air scoop/cowl was fitted to the top of the cylinder heads of Suzuki two-stroke engines to aid cooling.
