Ariel Square Four 4G1000

Ariel Square Four 4G1000
Manufacturer	Ariel
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

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.

Engine

The engine was a Air cooled cooled Four stroke, vertical square four, OHV, 8 valves. The engine featured a 6.0:1 compression ratio.

Chassis

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.

Photos

Overview

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 and—later— 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
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