FN (Fabrique Nationale de Armes, of Herstal) (Fabrique Nationale, de Armes de Guerre) was a Belgian company which made arms and ammunition and, from 1901 to 1967, motorcycles. FN was the world's first to manufacture a four-cylinder motorcycle and was famous for use of shaft-drive.
1899 established to make arms and ammunition
1899 FN made shaft and chain driven bicycles,
1900 Experimented with a clip-on engine.
1901 December: the first 133 cc single cylinder motorcycle was built
1902 the machines were represented by W. R. McTaggart
1903 Introduced a shaft-driven 188 cc single cylinder motorcycle, a famous development, used in all models from 1903 to 1923, successful in sprint and long distance motorcycle racing, and, after 1945, motocross.
1904 a 300 cc single cylinder motorcycle was produced.
1905 the first 362 cc shaft drive in-line FN inlet-over-exhaust four cylinder motorcycle appeared, designed by Paul Kellercom. This was the world's first manufactured four cylinder motorcycle.
By 1907 the four-cylinder (Four) engine had grown to 412 cc, and that year's single cylinder 244 cc FN motorcycle was the first bike with a multiple ratio belt drive system, using a patented variable size engine pulley.
1908 the US Export model was introduced. The Four had a 493 cc engine.
1909 the two-speed singles had camshafts to open the inlets, instead of the earlier "automatic" valves.
1910 the Four became 498 cc. This bike weighed 75 kg (165 lb) dry, and could do 40 mph (64 km/h).
Represented by the F.N. Motor Agency
From 1912 the Singles had a hand-lever clutch and foot pedal rear brake.
1913-1917 For a list of the models and prices see the 1917 Red Book
1913 The Fours had a two speed gearbox and clutch, at the rear of the shaft drive, and bicycle pedals were permanently replaced with footrests from then on.
1914 the FN "Type 700" 748 cc Four was released, with the gearbox at the rear of the engine.
1914 and Post-WWI FN was represented in Britain by FN (England) Ltd
Sources of Information
-  Wikipedia