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Bike Profile - Posted 16th March 2011

1950 Ariel Square Four 4G Mk1
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Ariel's four-cylinder Square has a reputation of being a gentleman's motorcycle. Some of them can be a little more lively. Meet the classic bike which bit back...

Very often, there's a good reason why an old bike was shoved into storage decades ago. In the case of this 1950 Ariel Square Four it was an excellent reason indeed. The 998cc four-cylinder machine worked hard during the 1960s, attached to a home-made sidecar which the enterprising owner had built out of a bedstead. The Square was an ideal machine for its regular duties, commuting to work and providing family transport for husband, wife and the four kids.

When unfettered by domestic bliss, the 1950 4G Mk1 Square could exceed 90mph, and its gentle power delivery provided ideal propulsion for the fully-laden outfit, giving smooth, seamless acceleration from low revs. 35bhp went an awful long way in those days! It helped that the 4G produced its peak power at just 5500rpm with a broad spread of tractable torque, so the pilot didn't need to continually cog-swap between the four ratios in the Burman box. 'Effortless' was a word often associated with riding the Square Four…

It's in there somewhere.... 1950 Ariel Square Four 4G Mk1, as found

…although it did take a little bit of effort to get it going in the first place, and that was how this particular 4G earned its place in limbo for four decades. Some time at the end of the 1960s, the owner went out as usual to fire up the Square and - unusually for the breed; they're not normally of a snappish sort - it bit back. And broke his leg!

Can you tell what it is yet?....

You can imagine the scene: rider retires injured, Square is laid up in high dudgeon, home-made sidecar disappears into the mists of time (or most likely the rag-n-bone man's wagon). Nothing happens to the Ariel for another 40 odd years and then - voila! - up it pops onto the auction scene this Spring. The Ariel is being sold at the Bonhams' sale at the Stafford Classic Motorcycle Show on April 24th 2011 and, as you can see, it just needs a little bit of Solvol and a tune-up…

'Experience Designed It'.... The Ariel, as conceived

The Square Four model was initially a twinkle in Edward Turner's eye back in the 1920s when he worked at BSA. Yes, the 1920s - and even then four-cylinder motorcycles weren't new. The first four-pot two-wheeler we know of was the 1901 Holden. Anyway, after moving to Ariel and enlisting the aid of engineer Bert Hopwood, Turner's idea was made into metal in 1931 in the shape of the first, 4F 500cc Square Four. Turner had really intended his overhead cam four-cylinder motorcycle to be a fast sportster but it wasn't to be: instead the Square became a heavy tourer, famed for its long legs and relaxed ride rather than outright performance. When Turner moved on from Ariel, Val Page continued the Square's developments and it grew to 600cc in 1936 and then an OHV 998cc.

'Age Corroded It'.... 1950 Ariel Square Four 4G Mk1, as dragged out of the shed

From 1939 the 998cc Square Four could be ordered with Anstey link rear suspension and this version of the model was the one offered immediately after the war, now with telescopic front forks instead of girders but keeping its all-iron engine which had a tendency to overheat. It was a massive machine for the time, weighing in at around 215kg, although the low saddle height of just 28-inches and good weight distribution made all that mass manageable.

'The Miracle Multi'....
Barn Finds on ....

A major redesign was needed for the Square to be suitable for the 1950s so for 1949 the new model 4G Mk1 was launched with an all-alloy engine running at just 6:1 compression. Although the bottom end was much the same as before the war, the cylinder head, valve gear, crankcases, rocker box and such were all overhauled. The magneto was replaced by coil ignition with dynamo lighting. The modifications helped the Square's cooling and reduced its weight to under 200kg, as well as giving acceleration something of a boost. Braking was provided by single leading shoe, seven-inch drum brakes at each end, and an eight-inch brake arrived in 1951. Fuel consumption wasn't spectacularly good for the time, at between 40 and 50mpg.

I've ridden worse.... 1950 Ariel Square Four 4G Mk1, as dragged out of the shed

In solo trim, test riders found the Mk1's 'combination of zestful performance and roly-poly handling diverting and, on the whole, congenial.' Motor Cycling were impressed and reported 'acceleration which gives 0 to 92mph in under half a minute!' They also reckoned that 'the new Squariel combines the docility of a sidevalve with the out-and-out performance that can be equaled by very few vehicles.' Those were the days, when speed trials were measured in half-minutes…

Another update in 1953 created the Mk2 4G which featured the model's fabulous four-pipe exhaust system. The Square went out of production in 1959 and all types are extremely sought after these days. As Jeff Clew said; 'it is very pleasing to know that Britain had a very practical four cylinder model on the road so long ago, with its cylinders arranged in a form that is still quite unique today.'

'Just needs finishing'... 1950 Ariel Square Four 4G Mk1, ready to restore...

The leg-breaking 4G Mk1 you see here is going under the hammer with an estimate of between £2500 and £4500. Now, that estimate is described as 'affordable' but we think it's also unrealistic. Postwar Squares in good running order sell for between £10,000 and £14,000 these days. A Square project in similar condition sold for nearly £7000 last year. So don't get excited about the idea of restoring this particular 4G Mk1, unless you're prepared to spend over £5000 on the purchase and a further £3000 or more on its restoration. If you would like to bid on it, then see motorcycles to register before the sale.

Words: Rowena Hoseason
Illustrations: Bonhams, archive


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