AJS Motorcycle

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A.J.S. Motorcycles - Models 16C 20 8 18CS 7R 16MS

This is one of many illustrated classic motorcycle guides I've created for the community. I hope you enjoy it. If you wish to find out more about the classic AJS motorcycle art featured in this guide please click here.

The first AJS motorbike was built in 1909 by the Stevens brothers at Wolverhampton. By 1927 they had introduced racing engines with chain driven ohc in 348cc and 498cc. In 1931 A.J.S. was sold to Matchless and moved to London. For many years following the merger, although the two bikes had many parts in common, the AJS marque remained a separate entity. This guide details six well-loved AJS motor cycles from the post-war period.

AJS Model 16MS

The basis of the AJS Model 16 MS was a long-stroke single overhead valve engine of 1935, the same as used in the wartime Matchless GL3. The orthodox but very tough push rod engine featured dry sump lubrication with an external oil tank. Flywheels were cast iron but were lightened for 1954. An all-alloy version of the engine appeared for competition models in 1950 with an alloy head for roadsters following in 1951. Further improvements to the model were made and despite the presence of the AMC "lightweight" single by 1960, sales of the old G3/Model 16 had actually increased by 1961 giving evidence of the loyalty to the long stroke formula.

AJS Model 8

In 1960 the AJS Model 8 appeared as a 350cc single. It featured a scaled up engine with a 20mm longer stroke, not simply a bored-out 250, having the same dimensions as the discontinued "heavyweight" 350 Model 16CS scrambler  of the previous year. The Model 8's engine differed from the 250 in having a compression of 6:9:1, an exhaust-valve lifter on the exhaust rocker, and ingenious flat-faced cast-iron flywheels. This scaled-up 250 was similar to BSA's enlarged C15 250, the B40 350, and was an attempt to deal with the criticism of the "heavyweight" Model 16 as a plodding, over laden, scaled down 500.

AJS Model 7R

Announced for the 1948 season, the handsome 348cc AJS Model 7R had little in common with the pre-war road-racing R7 AJS. A sleek black and gold beauty, it was similar to the rival Velocette Mk7 racer, which shared the same bore and stroke dimensions but it was lighter than the Velo, using magnesium-alloy crankcases, timing gear casing and conical wheel hubs and aluminium fuel and oil tanks. Nicknamed the "Boys Racer" the model was of course raced by the original factory team but was primarily intended as an over-the-counter racer for the ordinary club rider.

AJS Model 20

Once Edward Turner had come up with the Speed Twin for Triumph in 1938, other major British factories were forced to respond with their own versions of the vertical twin engine. The last manufacturer to unveil such a design in the export-or-die post-war years was Associated Motor Cycles, joining the fray in 1949 with a 500cc model in the two AMC marque liveries. The AJS version was known as the Model 20 and was a docile and comfortable machine, with useful torque for accelerating.

AJS Model 18CS

The basis of the AJS Model 18 500cc was a long-stroke single ohv engine from 1953, one of whose manifestations had been the Matchless G3L used by the British Army in WW2. The 18CS was produced between 1950 and 1964. Comprising of an all-alloy engine in a sprung frame, it was aimed more at scrambles use than trails. A feature when introduced were the "fat" rear suspension units that immediately became known as "jampots". They were an improvement over the slimmer versions as the internal pressure was lower but was still prone to variable damping as the temperature changed.

AJS Model 16C

Produced from 1959 to 1964, the AJS Model 16C was one of the most successful "mudpluggers" of its day. Similar to its predecessor the 16MC, the 16C employed a redesigned engine with a new long-stroke configuration of 74x81mm rather than the earlier 69x93mm. Valve diameters were increased and power output went up from 19 to 23bhp @ 6200rpm.

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