1954 Ariel Square Four Mark II


According to motorcycle legend, the first draft of the renowned Ariel Square Four engine was sketched out by Edward Turner on this inside of a cigarette packet.  He then hawked the design around various manufacturers, and it was taken up by Jack Sangster at Ariel, who produced the first prototype in 1930.
During the 1930s a 500cc was first produced for sale, followed by a 600cc, then a 1000cc for the late 1930s.  Post-war the bike was lightened and tweaked, but, whilst being well received, still suffered from overheating, as the two rear cylinders in the four did not get enough air to keep them cool.  It was with this problem in mind that the Mark II version was developed, with four exhaust outlets rather than two, which went a long way to resolving the issue.  These Mark II bikes became known as ‘four pipers’, with the previous version known as ‘two pipers’.
The fundamental engine design of all versions of the bike, namely the arrangement of four pistons in a square with two crankshafts geared to one another, was retained throughout the period that the bikes were manufactured, right up to 1958.  In addition, the plunger-type spring frame was also retained throughout.  Apparently a swinging-arm version was in design but never materialised.
Our bike is an early Mark II in very nice, largely original condition.  We have the old green 1960s logbook for the bike, as well as a modern V5.  In addition we have a dating certificate from Draganfly Motorcycles, which shows that reg. no.  ORW 291 was despatched to Chas E Cope and Sons Ltd on 3 December, with the bike being first registered on 8th January 1954.  The bike has retained the same frame and engine numbers shown on the certificate, V5, and green logbook, namely frame KR 136 and PL 116, as well as its original colour of black.
The bike has received a considerable amount of maintenance and restoration work in the last year or so including:
  • A new seat
  • A new Morgo oil pump
  • Cylinder head restored and rebored
  • New valves and guides fitted
  • New tappets
  • New .40in pistons fitted
  • Cylinder head rebuilt
In total, we have receipts on file for around £3000 spent in 2014 and 2015.
The bike now runs and rides beautifully.  It is a lovely Square Four, with some patina, excellent provenance, and ready to be ridden and enjoyed.
Price £12,500