The BMW 247 engine is an

air-cooled Air-cooled engines rely on the circulation of air directly over heat dissipation fins or hot areas of the engine to cool them in order to keep the engine within operating temperatures. Air-cooled designs are far simpler than their liquid-cooled ...

flat-twin 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 the same ti ...

motorcycle engine A motorcycle engine is an engine that powers a motorcycle. Motorcycle engines are typically two-stroke or four-stroke internal combustion engines, but other engine types, such as Wankel engine, Wankels and electric motors, have been used. Altho ...

with two valves per cylinder, also known as "

airhead An airhead is a designated area in a hostile or threatened territory which, when seized and held, allows the air landing of further teams and materiel via an airbridge, and provides the maneuver and preparation space necessary for projected oper ...

" boxer. The 247 engine was the successor of the in 1969 (MY 1970) introduced first modern BMW boxer engine; the BMW 246 engine of the /5 series. With minor and more significant updates (247/76 in 1976 and 247/M80 in 1981) it was used by

BMW Bayerische Motoren Werke AG, trading as BMW Group (commonly abbreviated to BMW (), sometimes anglicised as Bavarian Motor Works), is a German multinational manufacturer of vehicles and motorcycles headquartered in Munich, Bavaria, Germany. Th ...

beginning with the 1974 /6 series in its

motorcycles A motorcycle (motorbike, bike; uni (if one-wheeled); trike (if three-wheeled); quad (if four-wheeled)) is a lightweight private 1-to-2 passenger personal motor vehicle Steering, steered by a Motorcycle handlebar, handlebar from a saddle-style ...

from 1974 to 1995. Before 1981 the ignition was points ignition. From 1981, introduced in the R80G/S it used

electronic ignition Ignition systems are used by heat engines to initiate combustion by igniting the fuel-air mixture. In a spark ignition versions of the internal combustion engine (such as petrol engines), the ignition system creates a spark to ignite the fuel-air ...

Nikasil Nikasil is a trademarked electrodeposited lipophilic nickel matrix silicon carbide coating for engine components, mainly piston engine cylinder liners. Development Nikasil was introduced by Mahle in 1967 and was initially developed to allow W ...

cylinders, and a lighter

flywheel A flywheel is a mechanical device that uses the conservation of angular momentum to store rotational energy, a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, a ...

. A number of different models were on the market: *CS: the Classic Sport, with a engine. *GS: Gelände/Straße - winner of a number of the Dakar rallies. *RS: Renn (Racing) Sport *RT: Road Touring *S: with the

R90S The BMW R90S is a 900cc sport motorcycle produced by BMW from 1973 to 1976. BMW commissioned designer Hans Muth to oversee the R90S, which became the flagship of the boxer engined "/6" range. Sporting distinctive two-tone paintwork, a bikini ...

*ST: traße An road-styled G/S. Subsequent to the type 247 motor, BMW also built other air-cooled flat twin engines known as the Typ 248/1 used for the R45, the R65 and the R65LS BMW motorcycles. Before that they built

side-valve A flathead engine, also known as a sidevalve engine''American Rodder'', 6/94, pp.45 & 93. or valve-in-block engine, is an internal combustion engine with its poppet valves contained within the Cam-in-block, engine block, instead of in the cyl ...

and

OHV OHV may refer to: * Overhead valve engine * Off-highway vehicle, aka off-road vehicle * Off-roading * California State Parks California State Parks is the state park system for the U.S. state of California. The system is administered by the C ...

engines commencing with the R32 of 1923. After the type 247, BMW substantially changed the engine design to include partial

oil cooling Oil cooling is the use of engine oil as a coolant, typically to remove surplus heat from an internal combustion engine. The hot engine transfers heat to the oil which then usually passes through a heat-exchanger, typically a type of radiator kno ...

and four valves per cylinder, a design which was to become known as the " oilhead".

References

247, BMW 247 engine Boxer engines {{Motorcycle-stub