Ariel ‘Square Four’ Chopper The National Motor Museum Trust


1950 Ariel Square Four W136 Las Vegas 2019

Ariel stalwart John Shanks on his MkII Square Four at the Easter Bathurst Rally in 2007. What emerged was a 500 cc design with a chain-driven overhead camshaft, with the drive to the gearbox taken from the left-hand end of the rear crankshaft. It was in effect a doubled-up vertical twin, with the two cranks coupled by gears.


1952 Ariel Square Four F20 Las Vegas Motorcycle 2017

A similar model Mk II Square Four was released in 1953, still using the same 995cc engine but with a new four-pipe exhaust system. In all, 15,600 Square Fours were built over its 1931-'58 production. BSA discontinued Ariel production at the end of the 1958 model year.


1951 Ariel Square Four 4G Mk I Classic Motorcycle Pictures

The Ariel Square Four Mark I made its debut in 1949 and, at long last, saw the cast iron cylinder barrels and head changed over to aluminum alloy. The change to aluminum alloy shed 30lb from the weight of the bike but, even more importantly, brought much improved cooling because of the aluminum's far better heat dissipating characteristics.


Ariel ‘Square Four’ Chopper The National Motor Museum Trust

Ariel updated the 1956 Square Four with a hooded headlight and fork cover featuring a top panel with speedo, ammeter and light switch. At the lower end of the fork was a new full-width light alloy hub. Rear suspension was still provided by the plunger frame, and that remained until the end of the line in the 1959 model.


1953 Ariel Square Four for Sale CC751463

The Square Four went through a major revision in 1953, with a new cylinder head and manifolds, prompting a new sub-model designation, Mark II, which ran from 1953 through Ariel's final year, 1959. Prior to 1953, both cylinders on each side shared just one exhaust pipe, hence the nickname "2-pipes".


Restored Ariel Square Four 1952 Photographs at Classic Bikes Restored Bikes Restored

1958 Ariel Square Four. The Ariel 4G MK II was a square four cylinder allround motorcycle produced between 1936 and 1967. It could reach a top speed of 99 mph (160 km/h). Claimed horsepower was 43.99 HP (32.8 KW) @ 5500 RPM. Undoubtedly, the most famous bike produced under the Ariel marquee was the Square Four. It was produced from 1931 till 1958.


Ariel Square Four The Squariel Old Bike Australasia

Restorer Gary Athey found the Ariel Square Four he'd always wanted, and then rebuilt it to his own specification. By Greg Williams. by Jeff Barger. Engine: 997cc air-cooled OHV "square" 4-cylinder, 65mm x 75mm bore and stroke, 7.2:1 compression ratio, 42hp @ 5,500rpm (claimed) Top speed: 105mph (approx.) Carburetion: SU, variable choke.


1953 Ariel Square Four for Sale CC751463

1959 Ariel Square Four MKII Engine: 997cc air-cooled OHV "square" four, 65mm x 75mm bore and stroke, 7.2:1 compression ratio,42hp @ 5,500rpm (claimed) Top speed (approx.): 105mph Carburetion: Single SU, variable choke Transmission: 4-speed, chain final drive.


1958 Ariel Square Four Motorcycle For Sale

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Ariel 4F ‘Square Four’ National Motor Museum

The Ariel Square Four was one of the most glamorous and best known British motorcycles. In production for 27 years, it was a mainstay in Ariel's line of motorcycles. Its story begins almost 80 years ago when, legend has it, a young engineer named Edward Turner — later to find fame as boss of Triumph — sketched a "square four" engined motorcycle on the back of a cigarette pack.


Absolutely Beautiful 1958 Ariel Square Four Resto Mod

Equipped from mid-1946 with Ariel's telescopic front forks, the Square Four was one of only two full 1000cc production motorcycles to emerge from the British industry following the Second World War. The Square Four name played on a then-popular brand of pipe tobacco, 'Four Square'. The machine was, and was intended to be, unusual, even.


1958 Ariel Square Four S105 Las Vegas Motorcycle 2018

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 4F 500cc Square Four. This remarkably compact powerplant was slotted into a twin downtube chassis similar to that used by Ariel's 500 singles, using girder forks and a rigid back end.


Restored Ariel Square Four 1957 Photographs at Classic Bikes Restored Bikes Restored

The Square Four is a motorcycle produced by Ariel between 1931 and 1959, designed by Edward Turner, who devised the Square Four engine in 1928.At this time he was looking for work, showing drawings of his engine design to motorcycle manufacturers. The early engine with "two transverse crankshafts" was essentially a pair of 'across frame' OHC parallel twins joined by their geared central.


Restored Ariel Square Four 1952 Photographs at Classic Bikes Restored Bikes Restored

The first incarnation of the Ariel Square Four—the 4F.31 model—available from 1931. Complete with hand gear change that was used on a few early examples. Martin Squires. With custom-bike culture exploding in recent years, the history and importance of early two-wheeled machines are often overlooked. Stock Stories tells the tales of these.


Restored Ariel Square Four 1957 Photographs at Classic Bikes Restored Bikes Restored

Ariel's Square Four started life in 1931, designed by a young Edward Turner who drew his original idea for the Square Four on the back of a fag packet, and then took it to several manufacturers. BSA weren't interested but Ariel were willing to try it out. Turner was hoping to 'provide a four-cylinder engine small enough for use in a solo.


1947 Ariel Square Four T322 Las Vegas 2019

The Ariel Square Four 4F made its debut at the 1930 Olympia Motorcycle Show featuring an overhead camshaft 500cc with a hand shift for the Burman gearbox, which was integral with the crankcase. Overhead camshafts and unit construction were well into the future for most firms, so Ariel was a real pioneer.