The survivor: a 1910 FN four

It's always exciting to see a veteran motorcycle discovered, particularly when it's relatively complete and in "original" condition. The October 1947 edition of Australian Motor Sports carried a story about such a discovery: even then 1910 seemed long ago. An interesting twist to this story is that the machine still exists - in very much the same condition as it was then - perhaps waiting to be rediscovered.

1910 FN left A real masterpiece of over 3 1/2 decades ago. Note the mica windows in the sump for visual inspection while the motor is running.

VINTAGE MOTOR CYCLES - No. 5
The 1910 Shaft Drive F.N.

By J. BERSON

The old Belgian firm of Fabrique Nationale has always made interesting motor cycles, and up till 1939 their products were raced with fair success on the Continent. In the golden era of motor cycling in Australia - 1926 to 1932 - quite a few F.N.'s were brought into this country, both fours and singles. The couple of highly tuned 350 c.c. models that were raced in Western Australia did very well against the very hot competition then existing in that class. They had an extremely massive engine (with chain driven overhead camshaft), in a graceful and rather nice-handling double-cradle frame. One of these, after a very hard life, now spends its declining years in Kalgoorlie, where it seems to belong to nobody in particular, but is borrowed by any local clubman who should find himself without a mount for any special event. In spite of being fed a variety of witches' brews in the way of fuel, the old "nuisance"' has never disgraced herself.

However, although the F.N.'s even of those times are practically forgotten now, they were very modern when compared with that illustrated here. Just when this machine first saw the light of day is a matter of conjecture, but when purchased in 1911, she was very secondhand, so at the most charitable estimate she would be a 1910 model. But the atmospheric inlet valves would seem to indicate a greater age, and the writer's guess is that "she's forty if she's a day."

Nowadays, a four cylinder motor cycle doesn't get a second look, and shaft drive is here to stay. But a combination of these two features is still very rare. And more so is a small capacity straight four.

This veteran has four air-cooled cylinders, each cast separately. Heads, of course, are integral with the barrels.

Centrelines of numbers 1 and 2, 2 1/2 inches apart, 2 and 3 at 3 inches, and 3 and 4 2 1/2 inches. Side exhaust valves are used, actuated by a camshaft on the off side. Access to these can be had by first removing the inlet manifold. Cylinder dimensions are about 50 m.m. bore and 60 m.m. stroke, giving a capacity of some 118 c.c. per cylinder, and 472 c.c. for the four. The crankshaft is carried on three main bearings. Big ends are very broad, being a little over an inch wide. The big end caps are each held to the rod by four small cheesehead screws.

Offside of the engine showing the maze of manifolds and the method of mounting the engine to the frame. The magneto is in an inverted position. 1910 FN right

The carburettor now fitted is not the original instrument, and is a B. and B., a very modern-looking article, although it was installed about 1912. It supplies the mixture through a downdraught manifold, which is a masterpiece of snake-charming. This bears a quantity of solder, rather naturally, as it must have had considerable fatigue on account of its attachment to four separate cylinders and carrying the heavy carburettor. The bore of each manifold branch is approximately seven-sixteenths of an inch.

The 5/8-inch bore exhaust pipes have a rather elegant curve down to the expansion box, from which a venturi-shaped tailpipe emerges. From this venturi runs a pipe to the crankcase breather on the other side of the engine. The designer must have been keen on crankcase ventilation.

The Belgian Bosch FN 10 magneto is driven from the front end of the crankshaft, and the distributor from the front end of the camshaft. These components are just in the right position to collect the lot on a rainy day.

The flywheel is a very light shell enclosing the clutch, which has a plurality of plates. Clutch operation is by a Bowden-operated quick-thread device.

A spur wheel, outside the flywheel, drives the pinion on the front end of the propeller shaft. Only one ratio is available.

Front forks are of the bottom-link type, broadly reminiscent of the earlier Harley Davidson. The springs both impact and rebound, are neatly housed in telescopic covers. The upper linkage carries a bracket to accommodate the carbide lamp when required.

The upper portion of the frame is on the general lines of any contemporary machine, but the front down tube forks into two elliptical section cradle tubes, between which the engine is slung. At the front end of these tubes are the (apparently non-standard) footrests - way off in the dim distance when viewed from the saddle. This saddle, a very spartan affair, is 36 inches from the ground, to allow vigorous use of the pedalling gear as and when.

There is no offside chainstay, the propeller shaft housing. performing the function of a normal chainstay. There is a detachable bar above this - a solid piece of black-smithing in half-inch round, which would seem to indicate that a previous owner didn't fancy relying on this torque-tube business to hold the back end of the frame true.

The tank is 30 inches long, 4 1/2 inches deep, and 3 1/2 inches wide. The detachable oil compartment has a hand pump, which supplements the gravity feed, needle-valve-controlled, to a manifold from which there is a riser to a jet for each big end bearing. There are four little mica windows in the side of the crankcase through which the rider can check the proper functioning of the lubrication system. The single brake, actuated by a left-foot pedal or back-pedalling, is internal expanding and of 8 1/2 inches diameter by one inch wide. The back sprocket is inside the brake back plate, this being belled out and cut away to allow entrance and exit of the chain.

Weight would be well under 200 lbs., and the wheelbase is 54 inches. Tyres are 650 x 65 (26 in. x 2 1/2 in.), beaded edge, and carry the butt-ended tubes of the period.

1910 FN rear The very interesting arrangement of the shaft drive - the bar directly above the shaft was fitted by a previous owner - possibly to help locate the rear wheel.

The F.N. was located in Broken Hill, forgotten under many years' accumulation of odd building material and tools. The writer is greatly indebted to Mr. Dave Reynolds, an old resident of the town, for his kindness in handing over this magnificent piece of motor cycling history. Too few of such machines have been preserved intact, and to a student of motor cycle design the possession of one is most gratifying. The search for these "old and rares" is a protracted and arduous process, in the course of which one may find much chaff and very little grain. But no collection could have been a more worthy nucleus than this fine old F.N.

One or two comments come to mind.

Most features of the machine are in accord with a date of 1910-11, with the noted exception of the replacement carburettor. The original would have been the famous - or infamous - FN automatic carburettor. The motor with the spark plugs between the inlet and exhaust valves appeared for the 1910 model, as did the new oiling system described. Note that the positions of the plugs and the priming cocks have been reversed on this machine. The "10" part of the "FN 10" magneto designation refers to 1910 manufacture.

The observation that the footrests are "apparently non-standard" is an understandable one, but not correct. They are in fact exact to specification, appalling as they might look. I wonder who was responsible for that bit of design?

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Copyright Leon Mitchell 2001

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