The Ariel Motorcycle Company was founded in 1902, borne
out of the earlier bicycle business. The name Ariel originally comes from
their ultra-light first penny-farthing bicycle. For its life as a
motorcycle manufacturer, the company was based at Dawlish Road, Bournbrook,
near Selly Oak, Birmingham. In 1944 the business was sold to
maintained production at Bournbrook until moving it to their Small Heath
factory, the last true Ariel motorcycle being produced in 1967. Two Ariel
engines are referenced in period.
Ariel Red Hunter
Developed in 1932, the Red Hunter was the mainstay of the company –
becoming famed for their reliability (every engine was tested for at least
two hours before being used). It was a single cylinder engine produced in
a range of sizes, topping out at the magical 500cc. The engine was very
similar to others singles of the era, being pushrod-operated twin valve,
air-cooled. A tell-tale is the polished steel cam covers. Power output on
pump fuel was about 25bhp, somewhat low compared to a similar JAP. Like
the JAP, output was to a separate gearbox.
A variant of the Red Hunter motorcycle would be a mainstay of the Army
through the Second World War. It would also be popular with grasstrack
racers and trials riders, but it never really made a mark in 500s.
Red Hunter mounted in the rear of the Wenz American
special. Photo courtesy Bob Wenz
Ariel Square Four
The Square Four (sometimes nicknamed the Squariel) was developed in 1928
as that rare beast for the time, a four-cylinder motorcycle engine.
However, rather than the expected in-line layout, it was in fact more of a
pair of twins, merged into a single unit, with a central flywheel and a
single cylinder head. From above, the four cylinders formed a square
(hence the name), with a small exhaust manifold (for the forward and rear
cylinder) on each side of the cylinder head.
The original engine was a 500, with chain-driven
overhead valves. But by 1937 a 996cc version was produced. The versions
most likely used in competition were the 1949 redesign, which introduced
alloy head and barrels, giving 35bhp on pump fuel in standard
specification, or the 1953 Mk II (also known as the four-pipe as the
exhaust manifolds were replaced with separate pipes) which increased power
Neither engine could really hold a candle to readily available and
JAP alternatives, and there was insufficient
incentive to undertake the development work necessary to be competitive.
Ken Neve used a modified engine in his KN II, Whitby
had one in the GSW but changed to JAP and
Bob Wenz used a Red Hunter to create the first
American built car