Bradbury Motorcycles

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Bradbury Motorcycles for 1920

Bradbury 1920 2 ¾ h.p. Engine

Engine unit of the new 2 ¾ h.p. Bradbury lightweight. Note the duplex frame tubes, detachable cylinder head, and clutch in the countershaft pulley. A picture of the complete machine appeared in last week's issue.

Bradbury 1920 4hp

An all-purpose mount. The 4h.p. single-cylinder Bradbury, with partially-enclosed chain transmission, three-speed gear box and hand-controlled clutch

Bradbury 1920 6hp Twin

The 6 h.p. Bradbury, with twin cylinder, detachable head engine. Dual clutch control (hand and foot) is fitted.

Bradbury 1920 Frame

The double front down tube fitted to the 2 ¾ h.p. and 6 h.p. models.


Three Types: 2 ¾ h p. and 4 h.p. Singles and 6 h.p. Two-cylinder Models.

ONE of the oldest firms in the motor cycle industry, the famous Lancashire firm of Bradbury and Co., Ltd., of Oldham, has deservedly held an enviable reputation for the staunchness of its productions, both as regards engine power and frame design.

The main lines of previous models will be followed in the 1920 output of the firm, but one type, new to the general public (it was briefly described in The Motor Cycle March 2nd, 1916), is now being brought forward.

The 2 ¾ h.p. Lightweight.

This is of a type which will fill a gap in the market, since it is a homogeneous design, carried out entirely as the production of the firm who market it. Many motor cyclists do not care to have a machine built around a proprietary engine, preferring one in which the unit is exclusive to the particular make favoured, and, so far, they have not been able to indulge their fancy in this direction so far as small single-cylinder four-strokes are concerned.

The bore and stroke are 74.5 x 80 mm, respectively, the cylinder having a capacity of 349 c.c, the crank case being incorporated in the frame in the same way as that of the old-established 4 h.p. model. A detachable head is fitted, and this is held by long bolts and a bridging piece similar to those employed on the 6 h.p. engine. It will be seen, therefore, that the best points of previous Bradbury practice and experience are incorporated.

Adjustable tappets are used, and large diameter taper springs return the valves to the seatings. The timing gear is simple, and only has one half-time wheel, while a neat external exhaust valve lifter acts upon a large disc on the tappet stem. Carburation is effected by a top-feed B. and B., and a C.A.V. magneto, chain-driven, is carried before the engine above the cast aluminium silencer.

Frame Design.

The frame is exceedingly neat, being somewhat of a departure from standard practice. Its most noticeable feature is the duplex front tube. Following the design of the 4 h.p. frame this model dispenses with the usual tube under the tank, and has a straight top member free from bends, from which the tank is suspended by clips. This construction is not unduly high, and the Brooks saddle sits quite low at the rear angld of the frame. Commendable features are the employment of long tapered lugs and the short strengthening strut above the gear box bracket.


The power is transmitted to the road wheel through a two-speed box, chain-cum-belt drive being employed. A handle-bar controlled clutch is fitted in the large diameter belt-pulley on the gear box, while the gears are changed by a small lever working on a bracket attached to the top tube.

A smart tank, with rounded sides, is fitted, and this is equipped wjth a Best and Lloyd semi-automatic oil pump with sight-feed regulator.

The 4 h.p. Single.

This well-tried machine, equally suitable for solo or sidecar work, is justly popular. In the past the powerful "square" engine (89 X 89 mm. bore and stroke = 554 c.c) has earned a world-wide reputation for its slogging powers under adverse conditions. It now reappears with various detail improvements all-chain drive, and three-speed counters shaft gear. Constructional details remain the same as in the pre-war models, with the exception of the fact that Druid Mark 11 forks are fitted, and that the frame embodies a short stay from the gear bracket to the saddle tube.

All-chain Drive.

A B. and B. carburetter is fitted, and Thomson-Bennett magneto. Lubricatlion is by Best and Lloyd semi-automatic drip feed.

Transmission is by chains throughout, the Bradbury three-speed gear with kick starter and clutch being used. A Bowden control from the left handle-grip releases the clutch, and it is note worthy that the operating mechanism and cable adjustment on the gear box are easily accessible. The chains are partially enclosed, having a complete cover between the engine and gears, but only a guard over the top of the final drive, and an internal expanding brake operates in the rear wheel sprocket. A large shield before the magneto, long aluminium foot-boards, and a Brooks saddle respectively ensure the cleanliness and comfort of the rider.

The 6 h.p. Passenger Model.

As a powerful mount, suitable for side-car work in any district, the 6 h.p. V twin Bradbury has acquitted itself well. Little change has been found necessary in the general design of the machine, although a new type of frame is used embodying duplex front tubes such as are fitted to the 2 ¾ h.p. model.

Engine details remain the same, the bore and stroke being 74.5 X 86 mm. = 749.75 c.c. The neat cylinders, with detachable heads, are held by long bolts and bridges as heretofore.

Chain transmission is used throughout with the well-tried sliding pinion three-speed gear. A combined hand and foot control is fitted to the clutch, this being a point of great convenience, since both forms of clutch control have their advantages, especially when traffic driving with sidecar. In general specification this model resembles the 4 h.p. single, except that the rear chain guard is deeper and that a quickly detachable rear wheel is fitted. The Grindlay spring wheel side-car is fitted to these machines Avhen required, this make having been adopted by the Bradbury Co. as standard for its 1920 specification. The finish on these machines receives much attention, and is of high order, the rounded tanks, enamelled black with a broad gold line, being particularly handsome.

The Motor Cycle, November 6th 1919, pp 504-505

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