my friend Irjanto from Surabaya sent me pics of his bike.
its an 1909 FN four.
yes, FN the guns company.
I stole some data from the net:
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. 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, 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. 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.