List of AMC motorcycles
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This is a partial list of motorcycle models produced by the Associated Motor Cycles (AMC) from its foundation in 1938 to incorporations as Norton-Villiers-Triumph.
[edit] Matchless G80/AJS Model 18
These two models, essentially badg engineered versions of the same motorcycle were produced from 1949 to 1966. The two models were made in the same factory, the only major difference being the position of their chain-driven magnetos; in front of the cylinder on the AJS, behind on the Matchless.
It was effectively a design from the 1930s despite being manufactured 30 years later. The AJS was updated when a spring frame (sprung-heel) rear suspension was made available. (hence the 'S'). The suspension was a vast improvement on the rigid rear end which gave a bouncy ride but the wheel travel was still limited.
AMC then copied Velocettes twin-shock swingarm rear suspension design for its top AJS and Matchless singles and twins. Shorter vertical shock absorber units were introduced in 1949. One of these 'Candlestick' shocks held only 50cc of SAE 20 weight oil. Leak prone, they were replaced by the 'Jampot' shocks on the 1951 version.
The leaky pressed-steel primary chain-case first appeared on the 1953 G80S. In 1958 an alloy cover primary chain-case became available.
The engine was released with a compression ratio of 5.9:1, necessary because of because of the low quality fuel available in Britain immediately after the War. In 1949 the hairpin valve springs returned - conventional coil valve springs had been used in wartime production. By 1951 the G80 had an alloy cylinder head, and the barrel fins now went all the way to the base. The compression ratio was increased to 7.3:1 in 1956.
The low compression meant that it was easy to kick-start and was more flexible at low revs. The earlier long stroke version could not quite reach 80 mph but it could run happily at less than 20 mph in top gear. It also gave good fuel economy.
[edit] Technical Data
- Production : 1949-1966
- Engine type : Single cylinder, pushrod 2 valve, 4 stroke
- Capacity : 498cc
- Bore and Stroke:
-
- "Long Stroke" (1949-1955): 82.5 mm x 93 mm
- "Short Stroke" (1956-1966): 86 mm x 86 mm
- Compression Ratio
-
- (1949 - 1955): 5.9:1,
- (1956 on): 7.3:1
- Fuel System: 1 inch (27 mm) Amal carburettor
- Power:
-
- (1949 - 1955): 23 PS at 5,400 rpm
- Dry weight:
-
- (1949 - 1955) 177 kg
- Top Speed:
-
- (1949 - 1955) 78 mph
The 500cc "long stroke" G80CS and its AJS version, the 18CS were produced from 1951 through 1955. In 1956 they were replaced by the shorter stroke, larger bore models that used the same numeric codes. The bore of these early G80CS's was 82.5mm (3.25"), while the 1956 through 1966 “short stroke” (final version) models had a bore of 86mm. The C is for Competition (Scrambles) and the S for Suspension (not a rigid rear frame).
Engine numbers usually start with the year of production, followed by model designation, and completed with the production number of the motorcycle.
