A few weeks ago, MV Agusta debuted a prototype polygonal, square-esque engine at EICMA, and it was the talk of the town. The 5-cylinder engine, with three pistons in one row, and another 2 in the second, and driven by a weird U-shaped crankshaft, is said to have production intent, with the first motorcycle powered by the oddball coming likely late next year.
But MV Agusta's square engine isn't the first to attempt the design. Ariel Motorcycles, yes, the precursor to Ariel Motors and the makers of the awesome Nomad off-roader, once made a square engine for its bikes. In fact, RideApart covered the "Squariel" back in the day, and our friends over at The Autopian cited our original coverage when the MV dropped.
And that story, along with everyone else's coverage of the new MV Agusta motor and the history of square engines, likely put the motorcycle back in the zeitgeist. So much so that one intrepid owner of a Squariel likely thought, "Hey, maybe it's finally time to sell mine?" That seems to be the case with this new listing from Bring-a-Trailer and its Squariel auction subject.
The motorcycle in question is a 1953 Ariel Square Four, which is powered by Ariel's 997cc OHV four-cylinder engine and paired with a four-speed transmission. Four-cylinders aren't unheard of in the motorcycling world, obviously, but Ariel's square layout was one that was truly a weirdo within the industry.
According to our own Jason Marker, the man responsible for the Ariel Square Four was Edward Turner who, in 1928, set about creating an engine that was far better balanced, with less vibration, than other motorcycle engines of the time. His design was an "engine [with] a box-shaped mill with two opposing crankshafts and its four cylinders arranged in a square – two forward and two aft. It was, by and large, two parallel twins mated back to front on a common crankcase."
Marker added, "The crankshafts were coupled by geared central flywheels and rotated counter to one another. When it all worked correctly, two diagonally-opposed cylinders were at bottom dead center, while the other pair was at top dead center. In theory, this arrangement would cancel out the gyroscopic effects of the rotating assemblies, which would substantially reduce vibration when running. He called his engine the Square Four.
But the engine fell out of favor close to when this particular for-sale model came off the production line, with more and more folks looking for high-revving, smaller-displacement motorcycles. And Ariel ceased production around 1960 of the square engine. Who knew MV Agusta would basically revive it some 65 years later?
According to Bring-a-Trailer, "This 1953 Ariel Square Four was imported to the US from the UK in 2001, and it was purchased by the seller on BaT in September 2023. Finished in burgundy with gold pinstripes, the bike is powered by a 997cc OHV square-four paired with a four-speed transmission. Equipment includes a steering damper, a kick starter, a dual exhaust system, a sprung solo saddle, Anstey-link rear suspension, and both rear and side stands. Work under current ownership consisted of rebuilding the carburetor, changing the oil, and replacing the tires, spark plugs, oil and fuel lines, battery and box, and foot-control rubbers. This Square Four is offered with an owner’s manual, an Ariel Owner Motor Cycle Club Dating Certificate, an AMCA judging form, and a clean Florida title in the seller’s name."
As of this writing, the auction bid sits at $8,000, which ain't bad for a piece of history. Likewise, it'd get you a square-engined motorcycle ahead of MV Agusta's timeline, so if you don't want to wait for something weird to be in your garage, now's your chance.
