|Can you help?
We are looking for volunteers. If you are
a classic bike fan and can provide any of the following :
click here and send
us an email, we do offer incentives for published work.
|In the early fifties
the most popular British four-strokes were still pushrod singles.
500cc machines typical of this era were the Matchless G80 and the
AJS Model 18, both manufactured by Associated Motor Cycles (AMC) in
London. The two aforementioned models were made in the same factory,
the only difference in the two being the position of their chain-driven
The magneto in the AJS was in front of the cylinder, where the Matchless
was behind. The position of the magneto on the AJS allowed access
to the separate dynamo. The Model 18S was a little heavy but it offered
much better performance and fuel economy than the fast cars of the
A design from the 1930s, being manufactured 30 years on, the AJS was
updated when a spring frame rear suspension was included (hence the
'S'). The suspension was a vast improvement on the bouncy rear end
but the wheel travel was only 75mm.
A modest performance from the low compression
engine in 1950 was brought about by conditions in Britain at the ime.
Petrol rationing was abolished in 1950 but branded fuels did not return
to the High Street until 1953. If you couldn't get your hands on high-octane
aircraft fuel you were limited to standard low-octane 'Pool' petrol.
A compression ratio of 6:1 would have caused the engine to overheat
and damage the piston and valves.
The good thing about low compression was that it was easy to kickstart
and had more flexibility at low revs. The AJS wouldn't reach 80mph
but it would go along at less than 20mph in top gear. This meant that
a small amount of petrol went a long way.
AMC designed its own telescopic front fork
for the 1941 Matchless G3/L, but they chose to copy Velocette's twin-shock
swingarm rear suspension for it's top of the range AJS and Matchless
singles and twins. Shorter vertical units were introduced in 1949.
The 'Candlestick' shocks had only 50cc of SAE 20 oil in each damper.
They were prone to bottom-out and leak and had drain and filler plugs
which encouraged the owners to overfill the dampers, meaning further
leakage. 'Jampot' shock replaced these on the 1951 version.
Production : 1949-1963
Engine type : Single
cylinder, pushrod 2 valve, 4 stroke
Capacity : 498cc
Bore and Stroke : 82.5
Compression Ratio : 5.9:1
Fuel System : 27mm
Power : 23PS
Dry weight : 177kg
Top Speed : 78mph