Bleriot Motorcycles

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Bleriot Motorcycles

A Brief History of the Marque

Manufacturer : Blériot Aéronautique
3, Quai Galliéni


Pioneer French aviator Louis Blériot (1872-1936) produced motorcycles in the early 1920s. The first to fly the English Channel, Blériot also produced dynamos, starter motors and cyclecars.

His machines were quite advanced, featuring unit construction vertical twins of 500cc producing 5HP/12CV at 3000rpm to achieve 75kph, a respectable speed for the day.

The machines were offered in Sport, Tourist and Standard models, and a 750cc sidecar version was mooted. In 1920, the French police formed their first motorcycle squad, mounted on Bleriot machines.

The Blériot factory at Suresnes is now the site of Aerospatiale.


Bleriot spring frame and braking system. Disc wheels form part of the standard equipment,

Bleriot, 1919 Paris Salon

Quite one of the most important features of the Show is the fact that the well-known aircraft firm of L. Bleriot have decided to enter the motor cycle market. Their production is well worthy of its originators, and though some may cavil at the type of engine selected, and the somewhat "stumpy" appearance of the complete motor cycle, there can be no two opinions as to the ingenuity of the design, or the excellence of the construction. The engine is a vertical side by side twin, having a bore of 60 mm. and stroke of 88 mm. (499 c.c), having both connecting rods attached to a common crank pin.

The two cylinders of the engine are mounted close together, the exhaust valve being set in front and the inlet behind, both being of exceptional size. The valve springs are neatly enclosed by split covers, held together by spring rings. Combined with the motor is a two-speed gear box, having both trains of gears in constant mesh, a selective clutch mechanism being employed to determine the ratio. The change is normally carried out by means of a lever, but when the high gear clutch is in use a pedal provides an alternative method of declutching.

Lubrication is to a large degree automatic, a considerable quantity of oil being carried in the engine base. This oil is splashed to all working parts, including the clutch box, draining back to the base, and replenished when necessarily through a sight feed drip. The final drive is by belt running over a very large front pulley.

The frame is a sound piece of work, suspended in front by coil springs through a trailing link action, and the machine can be supplied with or without a spring frame. This springing is so neatly arranged as to be almost imperceptible, all springs being enclosed in the rear down tubes, and the necessary link action occupies but a small space. Both disc wheels are shod with 650 x 65 mm. tyres, and the rear mudguard is extended over the top of the belt rim.

Duplex tanks conceal the tank rails, and are joined on the lower sides by a combined tap and priming device.

As is the rule on French motor cycles, both brakes act on the belt rim, one above and the other below the chain stay, and the actuation is controlled by twin pedals placed side by side, so that either one or both brakes can be applied as desired. A refinement which will be appreciated by many is that the angle of the handle-bars is easily adjustable. Twist-grip controls are installed, and a special compartment for tools is arranged in the tank.

The Motor Cycle, October 1919

Paris Salon, 1919


Bleriot 500cc Twin 1921

Bleriot 500 c.c. side-by-side twin four-stroke, which embodies a concealed rear springing system. The disc wheels are built up from steel pressings.

Report on the Paris Salon. October 13th 1921

Side-by-side twin engines are favoured by the Bleriot Company, for, in addition to the four-stroke two-cylinder model now established on the French market, a twin two-stroke of 750 c.c. capacity is introduced this year - finished, in fact, a few days before the Salon opened. Like the four-stroke model, the gear box forms part of the crank case, the clutch is located between the two crank chambers, and there are three speeds and reverse, the latter, perhaps, more by accident than intention, since the power unit was designed for and is fitted in the new French Bleriot cycle car. The machine presents quite a good appearance, but there is still a certain amount of experimenting to be done before the model will be offered to the public, such points as economy and silence not yet having had very close attention.

The Motor Cycle

Bleriot 750 c.c. TWIN TWO-STROKE.

A Vertical Twin Sidecar with Three Speeds and Reverse to be at Olympia

BLERIOT FRERES, the well-known manufacturers of aeroplanes, motor car head lamps, dynamos, etc., have for some time been testing an entirely new model twin-cylinder two-stroke machine designed primarily for sidecar work. Although the engine is but of 750 c.c. capacity it is rated, in France at any rate, at the rather high figure of 8-10 h.p., the bore and stroke being 70 mm. X 96 mm.

This new model resembles the smaller Bleriot twin-cylinder four-stroke machine which has now been in commercial production for nearly three years, but possesses several novel and distinctive features. The clutch, of the disc type in which eleven discs are used, is contained within the flywheel, which is located centrally between the two cylinders, and these, as will be seen from the illustration, are spaced apart somewhat more widely than is usual in the case of vertical twin-cylinder machines. For the purpose of induction the two compression tight compartments of the crank case are located one on each side of the engine, and furthermore the casting is ribbed to assist cooling.

Unit Construction.

The three-speed gear box forms a unit with the engine, and an unusual feature is the provision of a reverse gear in addition to the three forward speeds. The change speed is effected in a novel and ingenious manner, the lever having only two positions on the quadrant, but also a vertical movement. In its normal position it operates first speed and reverse, a catch being provided which must be released before the lever can be made to bring the reverse into operation. For second and third speeds the lever must be pressed vertically downwards about three inches; it is then in position for bringing these two gears into action. All the rods controlling this gear are made adjustable, and the whole arrangement is actually less complicated than might be supposed from a brief description.

The petroil system of lubrication is used for the engine, grease, or a mixture of grease and oil, being used in the gear box. Dual clutch control is provided, and a kick-starter operates on the primary shaft of the gear box. Although final belt drive is shown in one illustration it is understood this machine will also be made with chain transmission.

The front forks and the frame generally are of substantial construction, the former being well provided with lubricators. A semi-cantilever type spring seat pillar is used and a front stand is fitted, though this latter looks somewhat fragile judged by British standards. An improvement in the arrangement of the exhaust pipes will be incorporated in later models in which a V-shaped union leads away to a centrally placed pipe passing between the double down tubes of the frame to the silencer underneath, which gives a neater and more symmetrical appearance to the machine. We understand that this machine will make its appearance in London at the November Show.

A very interesting "sports" type modification of the standard twin-cylinder four-stroke machine is also being produced for the coming season, and will be shown at the Olympia Show.

As in the case of the standard model the two cylinders, 50 x 88 mm. bore and stroke, work on the same crank, but in the sports model the heads are detachable and of true hemispherical form, with overhead valves operated by push rods and rocking levers, the former being placed side by side centrally in between the two cylinders, those for the exhaust in front and those for inlet at the back. This valve gear has been particularly neatly carried out, and the engine presents a thoroughly workmanlike job. As in the case of the standard model three speeds are provided, the camshaft which operates the inlet valves being arranged to serve also as the primary shaft of the gear box. The gears are always in mesh, changes being effected by means of selective dog clutches.

Not for Racing.

It should be added that this machine is intended simply as a "sports" model for use by the general public, and not specially for the most strenuous racing events, in which it is realised that a constant mesh gear box would probably be unsuitable. The new engine, we are informed, has done well over 4,000 revolutions and performs very satisfactorily on the road.

The standard touring model is now being marketed at a very interesting price, 3,975 francs in France, or £68 10s. at the present rate of exchange.

The Motor Cycle September 28th, 1922, p436

Sources: Tragatsch, fr.wikipedia.org, The Motor Cycle

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