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42-497: The engine is a flat-twin "oilhead" that has air-cooled cylinders but oil-cooled heads . Derived from the BMW R1100RS , the 1,085 cc fuel-injected eight-valve engine is tuned for a maximum output of 98 horsepower (73 kW) at 8,400rpm. At the time of its introduction, it was BMW's most powerful boxer engine ever made, and the first mated to a six-speed transmission. The ohv engine has chain-driven camshafts mounted in

84-402: A single-sided swinging arm encompassing shaft drive . The Paralever mounts directly to the frame instead of to the gearbox as on earlier oilheads. A reviewer reported: “The result is greater frame rigidity and better handling". A detachable tubular subframe supports the rider and passenger. The R1100S has a very substantial half fairing which completely envelops the alloy fuel tank. Both

126-512: A stressed member , the R1100S has a composite aluminum frame to which the suspension components are attached. The front suspension is BMW's patented Telelever , with long telescopic fork sliders containing neither springs nor damping. In order to minimize "fork dive" , braking forces are taken back to the frame via a pivoting wishbone. A monoshock on this wishbone copes with springing and damping. The rear suspension comprises BMW's " Paralever ",

168-565: A countershaft below the engine (as used by the Douglas Fairy), or a gearbox located above the engine, although in some cases the cylinders were short enough to use the gearbox in the traditional location behind the engine. In 1916, most flat-twin motorcycles still used a transversely-mounted engine. The European models at this time included the Bradbury 3.5 hp (2.6 kW), the Brough HB ,

210-510: A diesel version of its existing 688 cc petrol flat-twin in 1932, and went on to produce flat-twin diesel and petrol engines for a variety of industrial and marine uses into the 1950s. Two-stroke flat-twins were often used as outboard motors for boats, as they were smoother than single-cylinder engines. In the 1940s, they were largely replaced by straight-twin two-stroke engines, which were easier to start and no longer had excessive amounts of vibration. BMW R1200S The BMW R1200S

252-407: A flat-twin engine with the crankshaft in line with the frame (therefore the cylinders sitting sideways in the frame) is that an air-cooled engine receives the same amount of cooling for each cylinder. The Harley-Davidson XA , which used a flat-twin engine with the cylinders across the frame, maintained an oil temperature 100 °F (56 °C) cooler than a Harley-Davidson WLA with a V-twin with

294-638: A long history of flat-twin engine motorcycles, as do Ural (Russia) and Dnepr (Ukraine). In 1902, the Pearse monoplane (which would later become one of the first aircraft to achieve flight) was powered by a flat-twin engine built on a farm by a hobbyist inventor. This engine used the unusual design of a single shared crank pin and double acting pistons. In 1908, the French company Dutheil-Chalmers began production of flat-twin aircraft engines, which used two counter-rotating crankshafts. The Dutheil-Chlamers engine

336-461: A solo tail piece, a Tire-pressure monitoring system and a wider 6" rear wheel to accommodate a size 190 tire. Despite these refinements, overall the earlier R1100S has perhaps proved the more successful design. Motor Cycle News said of the R1200S: "As an oddball track motorcycle it works, but as an accomplished all-rounder it falls short of the standards set by the R1100S that preceded it." However,

378-414: A thick connecting rod. Each piston was also connected to the other crankshaft by two thinner connecting rods, causing the two pistons to move on the same axis. It also had the torque reaction of one crankshaft cancel the torque reaction of the other, cancelling torque reaction in the engine. Lanchester used this engine design until 1904. Other early uses of flat-twin engines were 1903-04 Ford Model A ,

420-509: Is a luxury sports motorcycle produced by BMW Motorrad from 2006 to 2007. Compared to the BMW R1100S which it succeeded, the R1200S was 13 kg (29 lb) lighter, and (with a compression ratio raised from 11.3:1 to 12.5:1) it was 25% more powerful with a "hexhead" motor rated at 122 horsepower (91 kW). Much of the weight saving was down to a new trellis-type frame which replaced

462-415: Is usually addressed by means of a crankcase breather. The Citroën 2CV boxer-twin engine took advantage of this pumping effect to maintain a partial vacuum inside the crankcase, in order to reduce oil leaks when an oil seal malfunctions. This was achieved by using a one-way valve (a leather or rubber flap over a hole in the crankcase), to let air escape the crankcase but not enter it. The beginnings of

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504-461: The BMW R1100RS from which it was derived, but at 229 kg (505 lb) (wet), it is still no lightweight. Nevertheless, What Bike? magazine stated: "With underseat exhaust and plenty of ground clearance, the BMW is helped by the lack of dive under braking and makes up metres on the entry to corners. Mid-corner speed is superb, but it's on the exit that the air-cooled twin shows its short legs. Stick to

546-906: The Douglas 2.75 hp (2.05 kW) and 4 hp (3.0 kW) models, the Humber 3.5 hp and 6 hp (4.5 kW) models, the Matchless 6 hp, the Montgomery 6 hp, Williamson Flat Twin 8 hp (6.0 kW), and the Bayerische Flugzeugwerke Helios (the predecessor to BMW's first motorcycle). Models produced in the United States included the Indian Model O and the Harley-Davidson Model W . The main benefit of mounting

588-514: The 1904-1905 Ford Model C , the 1905-1906 Ford Model F . and several Jowett Cars models from 1910 to 1937. The Citroën 2CV , produced from 1948 to 1990, was one of the first front-wheel drive cars to use a flat engine. The 2CV was powered by an air-cooled boxer-twin engine. Also in 1948, the Panhard Dyna X was released with front-wheel drive and an air-cooled boxer-twin engine. Other cars following World War II using boxer-twin engines were

630-529: The 1945-1954 Jowett Bradford van, , the 1961-1976 DAF Daffodil , the 1961-1978 Toyota Publica , the 1965-1969 Toyota Sports 800 sportscar and several front-wheel drive models from Citroën and Panhard . Several rear-engined cars were also produced with boxer-twin engines originally designed for motorcycles, such as the 1957-1975 Puch 500 , the 1957-1959 BMW 600 and the 1959-1965 BMW 700 . The Brazilian manufacturer Gurgel Motores used an in-house developed water-cooled boxer-twin engine (Enertron engine) and

672-595: The BMW R1100S, the BoxerCup Replika (or "BCR"), was available from 2003 to 2005. The BCR had twin Laser under-seat exhausts, braided brake lines, carbon-fibre cylinder head protectors, a carbon-fibre oil-catcher bellypan, uprated Öhlins suspension, and a shorter paralever torque arm which raised the rear end to quicken the steering and increase cornering clearance. Later BoxerCup and Sport models had matte black engines, with

714-596: The Czechoslovakian Praga B2 . The HKS 700E is an oil-cooled flat twin for ultralight aircraft that is currently in production. In larger aircraft, flat-twin engines have been used in auxiliary power units (APUs). A notable example was made by ABC Motors in the 1920s and 1930s. During World War II, the Riedel firm in Germany designed and manufactured a two-stroke flat-twin engine as jet engine starter motors for

756-749: The Junkers Jumo 004, BMW 003 and Heinkel HeS 011 jet engines The Maytag 'Model 72' flat-twin engines— produced from 1937 until some time between 1952 and 1960— were used in various applications including clothes washing machines. Electrical generators using flat-twin engines were built by Norman Engineering Company from 1932 to 1968 and by Douglas during World War II. Enfield Industrial Engines (part of Royal Enfield ) produced flat-twin two-stroke petrol engines during World War II which were used for generators and other military uses. After 1945, Enfield produced flat-twin diesel engines, with applications including farm and marine use. Coventry Victor introduced

798-457: The Supreme (the later model) all these problems were fixed with a rear-domed piston, crankcase mixers and refined ignition system . Most flat-twin engines use a boxer configuration for the crankshaft and are therefore called "boxer-twin" engines. In a boxer-twin engine, the 180° crankshaft moves the pistons in phase with each other, therefore the forces generated by one piston are cancelled out by

840-643: The Volkswagen air-cooled boxer-four in several models from 1988 to 1994. The Toyota U engine was an air-cooled flat-twin engine produced from 1961 to 1976. Introduced in the Toyota Publica subcompact car, the U engine was also used in the Toyota MiniAce small commercial vehicle and the Toyota Sports 800 sports car. The benefits of using a flat-twin engine mounted with the crankshaft running perpendicular to

882-467: The compression and exhaust strokes). This system is distributorless and requires only a single contact breaker and coil for the engine. The boxer-twin configuration can cause pressuring of the crankcase during each inward piston stroke and de-pressurisation during each outward piston stroke, since both pistons are moving inwards or outwards at the same time. This crankcase pumping effect (also found on single-cylinder engines and 360° parallel-twin engines)

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924-465: The cylinder heads, operating the valves via short pushrods and rocker arms. Engines produced after 2003 had dual ignition , with two spark plugs per cylinder. The compact close-ratio six-speed transmission is derived from the BMW K1200RS. Far from being a touring overdrive, the top gear gives 20 mph per 1,000rpm, so at 80 mph the engine turns at 4,000rpm. In addition to using the engine as

966-521: The cylinders and cylinder heads remaining silver. The raised suspension of the BCR increased cylinder head cornering clearance (compared to the standard R1100RS), but this somewhat compromised the motorcycle for normal town/road use. The BCR came with a standard engine management chip which was changed for a modified chip at the first dealer service. Despite the different chip, the Replika claimed no more power than

1008-460: The cylinders in line with the frame. A side benefit is that the cylinders provide protection to the rider in the event of a collision or fall, and keeps their feet warm in cold weather. The downsides are that the engine cannot be mounted as close to the ground (otherwise the cylinders can scrape the ground during cornering) and that it exposes the cylinders and valve covers to the danger of collision damage. Longitudinal mounting also means that

1050-522: The drivetrain from the chain and pulley design to a belt-drive system driven directly from the engine. Later developments of the Douglas motorcycle were made with the cylinders in line with the frame until the Second World War. Other early flat-twin motorcycles used a similar layout, with their cylinders aligned along the frame and therefore with the crankshaft running transverse to the frame. In 1914

1092-510: The flat-twin engine were in 1896, when Karl Benz obtained a patent for the design. A year later, his company Benz & Cie unveiled the first flat-twin engine, a boxer design called the "contra engine". In 1900, The Lanchester Engine Company began production of the Lanchester 8 hp Phaeton , which used a flat-twin engine. This engine had an unusual design of two counter-rotating crankshafts, with each piston attached to its crankshaft by

1134-425: The frame (therefore the cylinders being in line with the frame) are a low centre of gravity and that a belt-drive or chain-drive system can be used to transmit drive to the rear wheel. However, the downsides are uneven heat distribution (the front cylinder is more heavily cooled than the rear cylinder) and a longer wheelbase is often required due to the length of the engine. The first flat-twin motorcycle engine

1176-592: The frame to provide even cooling across both cylinders. Flat-twin engines were also used in several aircraft up until the 1930s and in various stationary applications from the 1930s to the 1960s. The Australian lawnmower manufacturer Victa also produced a flat-twin engine push mower from August 1975 to 1980 dubbed the ‘Twin 500’, and later the ‘Supreme’. These engines were manufactured in Canada. They are very sought after as only small numbers were produced, most likely due to ignition- and fuel-related problems in early models. In

1218-458: The hugger (after market option) and front fender are made of carbon-fibre. The two-into-one exhaust feeds twin silencers tucked up high beneath the pillion seat, like those on the Ducati 916 . Factory options originally available from BMW included electrically heated grips, ABS brakes and a belly-pan fairing. The R1100S is 27 kg (60 lb) lighter and 8 hp (6.0 kW) more powerful than

1260-445: The main supplier of rear-hub gearboxes, Sturmey-Archer , introduced a 3-speed countershaft gearbox with integral kick-starter, which posed a design problem for motorcycles with transversely-mounted flat-twin engines. This gearbox could be relatively easily located behind a single-cylinder or V-twin engine, however this arrangement would result in an excessively long wheelbase for flat-twin engines. Solutions to this problem included using

1302-455: The massive alloy frame of the R1100S. The R1200S thus had superior handling, improved braking, higher power output, greater ground clearance, and sport ergonomics. Although the instrumentation was updated, the bike retained the unconventional BMW-system indicator switches (one on either side). Factory options included front and rear Öhlins shock absorbers, switchable ABS , a light weight Akrapovič muffler, expandable locking luggage, heated grips,

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1344-458: The other, resulting in excellent primary balance. The evenly spaced firing order also assists in reducing vibration. The equal and opposite forces in a boxer-twin engine do however generate a rocking couple , due to the offset distance between the pistons along the crankshaft. A commonly used ignition system is wasted spark , which is a simple ignition system using a double-ended coil firing both spark plugs on each revolution (i.e. during both

1386-470: The owners’ comments attached to this article viewed the R1200S much more favourably. The 2006 BMW R1200S was reported to have a 0-60 time of 3.5 seconds, and a quarter mile time of 11.1 seconds. In 2008 the R1200S was superseded by the double overhead camshaft HP2 Sport . At 178 kg (dry) and 128 hp, the HP2 is even lighter and more powerful than the R1200S upon which it is based; (and compared to

1428-479: The road, though, and the R1100S is a great place to be". Motor Cycle News ( MCN ) later reviewed the R1100S, stating: "The BMW R1100S is now starting to be regarded as something of a classic, especially in BoxerCup form. Classy styling, VFR -esque comfort and versatility plus BMW quality and residuals make for a stonking and attractive all-rounder, if not quite the sports bike BM intended…". A special edition model

1470-467: The same time. The flat-twin design was patented by Karl Benz in 1896 and the first production flat-twin engine was used in the Lanchester 8 hp Phaeton car released in 1900. The flat-twin engine was used in several other cars since, however a more common usage is in motorcycles; early models oriented the cylinders in line with the frame, however later models switched to the cylinders being perpendicular to

1512-510: The standard R1100S nor the Sport. The R1100S was superseded in 2006 by the R1200S . The alloy frame of the R1100S was replaced by a lightweight tubular trellis and so, with a tuned engine, the R1200S was 13 kg (29 lb) lighter and 25% more powerful. MCN compared the R1200S to its predecessor this way: "As an oddball track motorcycle it works, but as an accomplished all-rounder it falls short of

1554-412: The standards set by the R1100S that preceded it." In 2008 the R1200S was itself superseded by the double overhead camshaft HP2 Sport . Flat-twin engine A flat-twin engine is a two-cylinder internal combustion engine with the cylinders on opposite sides of the crankshaft. The most common type of flat-twin engine is the boxer-twin engine , where both pistons move inwards and outwards at

1596-439: The torque reaction will twist the motorcycle to one side (such as on sharp acceleration/deceleration or when opening the throttle in neutral) instead of shifting the weight balance between the front and rear wheels. However, many modern motorcycles reduce this effect by rotating flywheels or alternators in the opposite direction to that of the crankshaft. One of the first motorcycles with a longitudinally-mounted flat-twin engine

1638-726: Was built in 1905 by the Light Motors Company in the United Kingdom. Originally named the Fée (renamed "Fairy" soon after its introduction), it was designed as a "bicycle engine system" which transmitted power to a pulley on the rear wheel via a chain. Manufacture of the Fairy was taken over by the Douglas Engineering Company , one of Light Motors' suppliers, when the Light Motors Company folded in 1907. Later in 1907, Douglas changed

1680-455: Was the R1100S Sport , which was a standard R1100S fitted with an optional "Sport" pack comprising stiffer suspension via a taller rear monoshock, a steering damper, and a wider rear wheel and tyre. Bike magazine commented: "The basic R1100S is good value, but we're not convinced that the high spec Sport version offers any real benefit for road riders". A more expensive track-day version of

1722-530: Was the 1916 ABC , which was built in the United Kingdom. To accommodate chain drive, the ABC used a bevel drive at the gearbox to change the direction of the drive through ninety degrees. BMW's first motorcycle, the 1923 BMW R 32 was another early example of a longitudinally-mounted flat-twin engine, although it this case the power was transmitted to the rear wheel via a shaft drive. Over time, longitudinal mounting became more common for flat-twin engines. BMW has

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1764-540: Was used by the 1907 Santos-Dumont Demoiselle No. 20 experimental airplane, with later versions of this airplane being produced with flat-twin engines from Darracq and Clément-Bayard . Most piston-engined aircraft used more than two cylinders, however other flat-twin aircraft engines from the 1920s and 1930s include the American Aeronca E-107 and Aeronca E-113 , the British Bristol Cherub , and

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