In 1899, FN made shaft- and chain-driven bicycles, and in 1900 experimented with a clip-on engine.
In December 1901, the first 133 cc single-cylinder motorcycle was built, followed in 1903 by a shaft-driven 188 cc single-cylinder motorcycle. In 1904 a 300 cc single-cylinder motorcycle was produced. The 1907 single-cylinder 244 cc FN motorcycle was the first bike with a multiple-ratio belt drive system, using a patented variable-size engine pulley. In 1909 the two-speed singles had camshafts to open the inlets, instead of the earlier “automatic” valves. Starting from 1912 the singles had a hand lever clutch and foot pedal rear brake.
In 1905, the first 362 cc shaft-drive in-line FN inlet-over-exhaust four-cylinder motorcycle appeared, designed by Paul Kelecom. This was the world's first manufactured four-cylinder motorcycle. By 1907 the Four engine had grown to 412 cc. For 1908, the US Export model began manufacture. The Four had a 493 cc engine, and in 1910 that became 498 cc. This bike weighed 75 kg (165 lb) dry, and could do 40 mph (64 km/h). The 1913 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. For 1914 the FN “Type 700” 748 cc Four was released, with the gearbox at the rear of the engine.
By the end of World War I, after having to manufacture motorcycles for their occupiers, FN had few parts left, and some suppliers had gone. From 1921 the letter "T" was added to model names. The Type 700T Four had a three-speed gearbox. In 1922 the Type 285TT single had an improved cylinder head. Also the first racer, the Type VII was built.
From 1924, all models had the less expensive chain drive. Most of these were sv and ohv 348 cc and 498 cc singles. There were also 596 cc ohv machines. From 1924 FN single-cylinder engines changed from semi unit construction (as seen in the last semi-unit single, the 1922 FN 285TT, in its last year of sale in 1924,) to unit construction engines (as seen in the new-for-1924 M.60). A new chain driven M.50 Four was released with a new Amac carburettor and front brakes. In 1931 a Villiers 198 cc two-stroke FN model appeared. In 1938, the M.12 992 cc air-cooled sv flat twin was built for military use, and the all alloy M.11 was released in 350 cc ohv, 500 cc sv and 600 cc sv models. Then World War II intervened. An M.12 Tri-car was developed and produced for military use.