AJS Motorcycles

Today in Motorcycle History

AJS 1931 Models

Production moved from Wolverhampton to London

AJS announced their 1931 range in September, consisting of 10 models. The company was impacted by the by the 1929 Wall Street crash and had made a loss of £89,201.0s.0d in the financial year up to August 1930 and sales had not come up to expectations.

The government had introduced a special reduced Road Fund Tax of £1.10s.0d for motorcycles weighing less than 224lbs in an attempt to stimulate sales and aid the hard pressed motorcycle industry. AJS responded with three models designed to fall into the new concessionary tax band. Two were overhead valve models; the 2.48hp SA12 twin-port developed from the existing S12 model costing £40.0s.0d, and the 3.49 hp SB6 "Big Port" at £45.0s.0d. The third was the pretty little SA5 sidevalve model which weighed in at 221 lbs when fitted with a Maglita lighting set.

Unfortunately, despite the introduction of these models together with lower specification versions of the S8 and S4 the economic situation did not improve for the firm and the company went into liquidation on the 2nd October 1931.

S2 84 x 90mm 998cc V-twin
S3 498cc V-twin SV 65 x 75mm
S4 74 x 93mm 400cc
S5 74 x 81mm 348cc SV
S7 OHC 70 x 90mm 346cc Competition
S8 OHV 84 x 90mm 498cc
S10 OHC 79 x 101mm 495cc Competition
SA12 OHV 65 x 75mm 249cc Twin-port
SB6 74 x 81mm 348cc
SB8 84 x 90mm 498cc

AJS S9 1931 500cc SV
Displacement: 500 cc
Type of engine: single-cylinder, four stroke, side valve
Transmission: chain drive, three speed gearbox.
Suspension: parallelogram front forks, rigid rear.

The S9 was available in two versions, "Light" and "Heavy". There are several differences between the two: rear chain size, gear ratios, wheel base and petrol and oil tank capacity. The engine is the same in both versions.

AJS 498cc Model 9 Specifications

1931 A.J.S. Models.

More Speed and More Comfort.

Although the new 1931 A. J.S. machines which are announced to-day are not vastly different in design to the 1930 models, they strike a note of even greater refinement.

THE writer looked one of the new machines over yesterday. The neat instrument panel mounted on top of the petrol tank is a pleasing feature, and the cleaner design of the engine also is noteworthy. In the side-valve engines the tappets are enclosed by a well which is cast integral with the cylinder barrel, thereby making the engine completely oil-tight., The valves are now set in the cylinder barrel, the head merely performing the function of completing the combustion chamber. Unis allows the head to be made of aluminium and the better heat radiation of this metal, coupled with an increased fin area, gives a double improvement in engine cooling.

All models are now fitted with an entirely new cushion-drive shock absorber, which is extremely efficient, and gives smooth running at slow speeds.

A better saddle suspension and longer springs make a further improvement to the comfort of the rider, and heavier front spindles make the 3 1/2 h.p. models even more suitable for sidecar use.

Throughout all models there is quite an amount of refinement in detail. Low stands make it easier for the llder to park, and although the real wheel is barely raised from the ground its removal is made extremely simple by a combination of the A J S patent quick detachable design and a rear mudguard which is hinged, allowing the tail only to be raised after loosening two nuts Two other features worth special mention are the clean handlebar assembly, with all the control wires running through the handlebars, and in improvement in the lubrication system

The question of the value of racing has for years been a subject of acute controversy, with worthy protagonists on each side, but the attitude of A J Stevens and Co appears to be thoroughly logical. Although AJS machines have more Tourist Trophy wins to their ciedit than any other make, speed in itself has never been the paramount consideration. On the other hand, experience gained in high speed work has undoubtedly assisted in improving the design of standard machines.

The new AJS models will be on view to-day at the showroom of the Queensland agents, British Motor Cycle Co, Ltd , Adelaide Street, Brisbane.

The Brisbane Courier Thu 18 Dec 1930

Sources: H&H Classic Auctions, Trove NLA, et al

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