AJS Model 18: history, specs, pictures

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AJS 18S 500.jpg
AJS Model 18 500
Also called 'The Statesman' (mid-1960s only). Ajay. Jampot.
Production 1945 - 1966
Class Classic
air-cooled, four-stroke, single cylinder, OHV, 2 valves, pushrod
Bore / Stroke 81.3mm x 81.3mm
Compression ratio 6.9:1
Horsepower 28.03 HP (20.9 KW) @ 5600RPM
Transmission Gear box: 4-speed, manual

Final Drive: chain

Clutch: wet multi-disc, manual
Suspension Front: telescopic fork
Rear: dual shocks
Brakes Front: drum
Rear: drum
Front Tire 3.25 -19
Rear Tire 34.25 -19
Wheelbase 55.12 inches (1400 mm)
Seat Height 29.88 inches (759 mm)
Weight 160.0 kg (wet)
Fuel Capacity 4.23 Gallon (16.00 Liters)
Manuals Service Manual

The AJS Model 18 500 Statesman and AJS Model 18S were both single cylinder, four-stroke 500 cc British motorcycles produced between 1960 and 1965. Claimed horsepower was 27.36 HP (20.4 KW) @ 5600 RPM. They were almost identical to the Matchless G80 and both were produced in the same Associated Motor Cycles (AMC) London factory from 1945 to 1966. These bikes represent the end of the era of big British singles, as when AMC merged with Norton production concentrated on twins.

Development[edit | edit source]

The AJS Model 18 was developed from a design from the 1930s, despite which it was still being manufactured 30 years later. The AJS was updated when a springer frame rear suspension was made available for 1949, to become the Model 18S. The suspension was a vast improvement on the rigid rear end - which had given a bouncy ride. Each of the two 'Candlestick' shocks held only 50 cc of SAE 20 weight oil. They were prone to leaks and were replaced by the larger diameter 'Jampot' shocks on the 1951 version.

Engine[edit | edit source]

The engine was a air cooled single cylinder, four-stroke. A 86.0mm bore x 85.5mm stroke result in a displacement of just 498.0 cubic centimeters.

Drive[edit | edit source]

The bike has a 4-speed transmission. The final drive was via chain. Power was moderated via the wet multiplate.

Chassis[edit | edit source]

It came with a 3.25-18 front tire and a 3.25-18 rear tire. Stopping was achieved via expanding brake (drum brake) in the front and a expanding brake (drum brake) in the rear. The front suspension was a telescopic while the rear was equiped with a twin shock. The Model 18500 Statesman is fitted with a 4.23 Gallon (16.00 Liters) fuel tank. The bike weighs just 379.2 pounds (172.0 Kg). The wheelbase is 55.0 inches (1397 mm) long.

1945 - 1966 AJS Model 18 500[edit | edit source]

1945 - 1966 AJS Model 18 500

The 1945 AJS Model 18 500 has, at its heart, an air-cooled, four-stroke, 498cc, single cylinder powerhouse paired to a four-speed manual transmission, and can reach a maximum power output of 28 horsepower at 5600 rpm.

This classic two-wheeler was addressed for a wide variety of riders, and came standard with features such as laced wheels, a telescopic front fork, dual shocks as a rear suspension, a drum braking system, a two-piece, dual seat with a sprung rider seat, a 13-liter (4.2-gallon) fuel tank and a chromed exhaust system.