Ariel Square Four 4G1000
It could reach a top speed of 4G: 141 km/h / 87 mph Mk I: 145 km/h / 90 mph Mk II: 160 km/h / 100 mph.
Ariel Square Four 4G1000 | |
Manufacturer | |
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Production | 4G: 4 288 Mk I: 3 922 Mk II: 3 828 |
Engine | Four stroke, vertical square four, OHV, 8 valves |
Compression ratio | 6.0:1 |
Top Speed | 4G: 141 km/h / 87 mph Mk I: 145 km/h / 90 mph Mk II: 160 km/h / 100 mph |
Transmission | 4-Speed |
Frame | Single down tube |
Suspension | Front: Telescopic fork Rear: Plunger-link spring |
Brakes | Front: Drum Rear: Drum |
Wheelbase | 1422 mm / 56 in |
Weight | 4G: 211 kg / 465 lbs Mk I: 197 kg / 435 lbs Mk II: 193 lg: 425 lbs (dry), |
Fuel Capacity | 23 L / 6.0 US gal |
Manuals | Service Manual |
EngineEdit
The engine was a Air cooled cooled Four stroke, vertical square four, OHV, 8 valves. The engine featured a 6.0:1 compression ratio.
ChassisEdit
Stopping was achieved via Drum in the front and a Drum in the rear. The front suspension was a Telescopic fork while the rear was equipped with a Plunger-link spring. The Square Four 4G1000 was fitted with a 23 L / 6.0 US gal fuel tank. The bike weighed just 4G: 211 kg / 465 lbs Mk I: 197 kg / 435 lbs Mk II: 193 lg: 425 lbs. The wheelbase was 1422 mm / 56 in long.
PhotosEdit
OverviewEdit
Ariel Square Four 1000
Ariel's parent company went bankrupt in 1932 when Jack Sangster bought the
rights to the Ariel name and much of the tooling at a reduced cost and started a
new company called Ariel Motors (J.S.) Ltd.. After the Second World War, Ariel
voluntarily allowed itself to be absorbed by the BSA empire.
One of Ariel's most
notable engines was the Square Four, the first prototype emerging in 1930. As
the name suggests, the cylinders were configured with two cylinders directly
behind the front two cylinders. Starting as a 500cc engine, then increased to
600cc and finally the 1000cc configuration. The 'Squariel' was plagued with heat
problems as one might imagine having two cylinders directly behind the front
pair. Despite the heat issues it remained in production until 1958
It is an oft-told part of motor cycling folklore
that London-born Edward Turner sketched out his idea for an entirely new type of
four-cylinder engine (with the cylinders arranged two by two in a square) on the
inside of a cigarette packet, took a train to the Midlands and hawked the scheme
all around the British motor cycle industry.
The people at AJS were tempted, but turned it
down after second thought. Yet there was a good fairy waiting in the wings after
all, in the form of Jack Sangster, chief of the Ariel factory. He gave Edward
Turner his chance, and the outcome was a machine that took the 1930 London
Olympic Show by storm. The same exhibition saw the coming of a rival
four-cylinder machine, a narrow-angle mono-bloc design from London's Matchless
factory, known as the Silver Hawk. Good as the Silver Hawk may have been,
however, it was destined to live in the shadow of the Ariel Square Four and,
after a few years, it had faded from the scene.
Turner's new Square Four engine was, in effect, a
pair of vertical twins (although with all four cylinders in a single casting)
with their crankshafts coupled by central spur gears. Three of the crank throws
were overhung, or single-sided, the fourth was a full crank, with an output
shaft which provided the primary drive to the gearbox. Originally Turner had
planned a unit-construction engine, light enough to be fitted into the standard
Ariel 250cc frame and with a horizontally split crankcase assembly. For policy
reasons (the Ariel works had a contract with Burman, the gearbox manufacturer) a
separate engine and gearbox were used for the production versions.
The first Square Four was a 500cc model with a
single, chain-driven overhead camshaft, but before long the capacity had been
raised to 600cc, the smaller model being dropped after a couple of years in
production.
Inevitably, the new machine attracted the attention .of those who wanted to make
it go a whole lot quicker than the makers had intended, and these included
Cambridge University clubman Howard Somerville Sikes, and Brooklands speed
specialist Ben Bickell. Both had the idea of building supercharged 500cc Square
Fours, but each for different reasons. Sikes wanted his for the 1931 Senior TT,
while Bickell had the aim of covering one hundred miles in an hour.
Unhappily, both men were thwarted for the less,
in the course of an endurance test for which the Ariel company gained the
coveted Maude's Trophy, a 500cc Square Four did succeed, under ACU observation,
in packing 700 miles into 700 minutes.
In the late 1930s the Square Four underwent a
complete redesign to emerge as a 997cc pushrod-overhead-valve model for which
the claim of 'ten to a hundred in top gear' was made. Indeed, it was the sheer
effortlessness of the Ariel's power delivery that was its greatest charm. As
time passed, however, so the initial concept of a relatively light-
weight four seemed to have become obscured, each refinement (such as the
compensated-link rear suspension system) adding just a little more weight.
Finally, it was decided to put the model on a
slimming course, resulting in the two-pipe andlater four-pipe all-light-alloy
fours of the post-war years. Yes, post-war, because the Ariel Square Four did
not die until 1958, and in the eyes of many enthusiasts the last models were the
best that were ever produced.
Make Model | Ariel Square Four 4G 1000, Mark I, Mark II |
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Year | 4G: 1936 - 48 Mk I: 1949 - 53 Mk II: 1953 - 58 |
Production | 4G: 4 288 Mk I: 3 922 Mk II: 3 828 |
Engine Type | Four stroke, vertical square four, OHV, 8 valves |
Displacement | 997 cc / 60.8 cu in |
Bore X Stroke | 65 x 78 mm |
Cooling System | Air cooled |
Compression | 6.0:1 |
Exhaust | Mk I, Mk II: 2 x 2-into-1 |
Induction | SU carburetor |
Starting | Kick start |
Max Power | F4 G, Mk I: 26 kW / 35 hp @ 5500 rpm Mk II: 34 kW / 45 hp @ 5500 rpm |
Transmission | 4-Speed |
Final Drive | Chain |
Frame | Single down tube |
Front Suspension | Telescopic fork |
Rear Suspension | Plunger-link spring |
Front Brakes | Drum |
Rear Brakes | Drum |
Wheels | Steel, laced wire spokes |
Dimensions | Length: 2100 mm / 82 in |
Wheelbase | 1422 mm / 56 in |
Dry Weight | 4G: 211 kg / 465 lbs Mk I: 197 kg / 435 lbs Mk II: 193 lg: 425 lbs |
Fuel Capacity | 23 L / 6.0 US gal |
Top Speed | 4G: 141 km/h / 87 mph Mk I: 145 km/h / 90 mph Mk II: 160 km/h / 100 mph |