The AJS 7R was a British 350 cc racing

motorcycle A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...

built from 1948 to 1963 by

Associated Motor Cycles Associated Motor Cycles (AMC) was a British motorcycle manufacturer founded by the Collier brothers as a parent company for the Matchless and AJS motorcycle companies. It later absorbed Francis-Barnett, James, and Norton before incorporation i ...

. It was also commonly known as the ‘Boy Racer’, and won victories both for the factory and for privateers right from its introduction in 1948.

The AJS 7R

A new design by Phil Walker, the chain-driven overhead camshaft 7R had the history of the pre-war AJS ‘cammy’ singles behind it. Initially, the 7R was not quite as powerful as its competitors, producing at 7500 rpm. The duplex frame and Teledraulic front forks remained relatively unchanged during production, while the engine had a number of changes. The included valve angle was progressively narrowed, and the

crankshaft A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecting ...

strengthened. In 1956 the engine dimensions changed from the original long-stroke 74 x 81 mm to the ‘squarer’ 75.5 x 78 mm. The AMC

gearbox Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differe ...

replaced the older

Burman Burman is a surname. Notable people with the surname include: * Anneli Burman (born 1963), Swedish curler *Barney Burman, American make-up artist * Barry Burman (1943–2001), English figurative artist * Ben Lucien Burman (1896–1984), American ...

unit in 1958.

AJS 7R3

In 1951 AJS development engineer Ike Hatch developed a 75.5 mm bore x 78 mm stroke, three valve head version of the 7R making . It was called the AJS 7R3, and was Ike's response to the Italian multi-cylinder racers. They did well enough in their first year, not as well the second. For 1954 Jack Williams, the works team manager, developed the bike further, lowering the engine in the frame, and making some tuning changes that gave @ 7800 rpm. It immediately won the first two rounds of the World Championship and took first at the

Isle of Man TT The Isle of Man TT or Tourist Trophy races are an annual motorcycle racing event run on the Isle of Man in May/June of most years since its inaugural race in 1907. The event is often called one of the most dangerous racing events in the world ...

. These were factory specials, but one has survived, and a second has been reconstructed from spares.

Racing

The 1957 AJS 7R 350 cc, with 75.5 mm bore and 78 mm stroke, gave at 7600-7800 rpm, and weighed 285 lb (129 kg). The top speed was 180-190 km/h (115-120 mph). AMC withdrew from the world of works, and one-off, road racing at the end of the 1954, with the death of Ike Hatch, and in the face of fierce competition from the other European bikes. After this AJS made a production version of the standard two valve AJS 7R, for privateers and a 500 cc version, badged as a

Matchless G50 The Matchless G50 is an historic racing British motorcycle made by Associated Motorcycles (AMC) at the former Matchless works in Plumstead, London. Developed in 1958 from the 350 cc AJS 7R, but with the engine capacity increased to 500 ...

was also sold. By the end of production in 1963 the two valve

OHC An overhead camshaft (OHC) engine is a piston engine where the camshaft is located in the cylinder head above the combustion chamber. This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combustion cha ...

AJS 7R engine made over . Swedish rider

Bill Nilsson Bill Nilsson (17 December 1932 – 25 August 2013) was a Swedish professional motocross racer. He competed in the Motocross World Championships from 1952 to 1967. Nilsson was the first 500 cc motocross world champion after winning the inaugur ...

converted an AJS 7R road racing machine into a

motocross Motocross is a form of off-road motorcycle racing held on enclosed off-road circuits. The sport evolved from motorcycle trials competitions held in the United Kingdom. History Motocross first evolved in Britain from motorcycle trials competi ...

bike and rode it to win the inaugural F.I.M. 500cc

Motocross World Championship FIM Motocross World Championship is the premier championship of motocross racing, organized by the Fédération Internationale de Motocyclisme (FIM), divided into two distinct classes: MXGP and MX2. Race duration is 30 minutes plus two laps per ...

held in 1957. AJS 7Rs won the 1961, 62 and 63 Junior

Manx Grand Prix The Manx Grand Prix motorcycle races are held on the Isle of Man TT Course (or 'Snaefell Mountain Course, Mountain Circuit') every year for a two-week period, usually spanning the end of August and early September. New for 2022 is a period re ...

races and came second in 1966.

Sources

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The AJS 7R

AJS 7R3

Racing

Sources

See also