FN 1903 2 ½ HP 320 cc two stroke special frame # 12750 engine # 9438
FN (Fabrique Nationale d‘Armes de Guerre) was a Belgian company established in 1889 to make arms and ammunition for hunting and warfare. Soon it was decided that diversification of production was a good strategy to reduce the risk of peaceful times. In the late 1800’s the production of bicycle parts was taken up; soon complete bicycles were added to the programme, followed in 1900 by motorcars. At that time FN was already a major manufacturing firm, with premises taking up around 30 acres with 40,000 square metres of factory buildings.
By the end of 1901 the first motorized bicycle was presented, powered by a 133 cc clip-on engine. It got the nickname “little donkey”. It was followed in 1903 by a 188cc model. Early in 1904 the capacity was enlarged to 300 cc. From 1905 on the four cylinder was catalogued and the single was further developed as a light model. The popularity of FN motorcycles is shown by the high sales figures: between July 1902 and July 1904 some 6,000 machines were sold.
The engine of the machine we offer here has been ingeniously converted to a two stroke. In order to get compression in the crankcase the space under the piston must be sealed. This was achieved by placing an intermediate piece between the cylinder and the crankcase. Because a movable connecting rod can’t be sealed, a round rod that only moves up and down was used. This ends on the crankshaft in a long rectangular guide. Inside this is a sliding block made of bronze, which goes back and forth when the shaft rotates, thus converting the kinetic energy of the piston into a rotary movement. It is the same principle and operation as in the steam engine between the piston and the crosshead. The shaft that comes out of the bottom of the engine is just an additional guide and consists of one part together with the guide rectangle and connecting rod. The petrol tank has two compartments, the front part holds the petrol and the rear part contains the castor oil to lubricate the piston and the membranes. In the separate oil tank under the saddle is the oil that feeds the drip oiler for the crosshead mechanism. On top of the cylinder we find the decompression valve. Its exhaust gases are directed into the crankcase. The gases that are expelled from the engine through slits in the cylinder wall go directly into the air, there is no exhaust system. This well-restored, unorthodox but fascinating machine is a real eyecatcher and comes with flat drive belt, mudguard mascotte, bicycle lock and pocket watch in holder on the handlebars.