The 1958 Ariel Square Four MkII is a legendary machine with exceptional performance for a 1950s motorcycle, and this low-mileage example has been restored to an exceptional standard. Ariel’s 4G model is nicknamed the Squariel for its four-square, twin-crankshaft design, and it was the only 4-cylinder motorcycle produced in any quantity in Britain before the contemporary Triumph factory was built in the 1990s. It’s also among longest-produced 4-cylinder motorcycle designs in the world. The motorcycle’s unique twin-crankshaft design provides perfect balance and smoothness and gives stunning performance; these late MkII models could be ridden in top gear from 10 MPH to 100 MPH, as the motor has tremendous flexibility.

The Square Four concept was originally designed by Edward Turner in 1928 as an overhead-camshaft 4-cylinder roadster, which Ariel produced as the 1931 Model 4F, with an initial engine capacity of 500cc, which was stretched to 600cc in 1932. These early machines were sophisticated, quick and smooth, but tended to run hot. The motor was totally redesigned in 1936 with a full 1000cc, becoming the 4G model, although it lost its overhead camshaft and became a more complex pushrod OHV machine. The 1000cc Square Four is a real Superbike, with a top speed of 90 MPH for the first, iron-head versions, with civilized road manners. After the war, the Square Four was reintroduced as Mark I, which weighed 435 pounds and had telescopic forks up front and a sophisticated trailing-link/plunger rear suspension, the “Anstey Link.”  With its all alloy engine and four graceful exhaust headers the featured final Mark II Square Four was a very sleek machine. The Square Four chassis evolved to plunger rear suspension with a rigid mounted dual seat. 1958 marked the last production of the Four.

This Ariel with its period correct British Watsonian Sports Squire sidecar makes an impressive combination. The sidecar can be easily removed for solo riding. WE will consider selling this sidecar separately for $6,000 but we feel it's a shame to break the pair.

Our Ariel SQ4 is in excellent condition, it has been in a large private collection and ridden regularly the past 30 years. This was his favorite motorcycle of his over 30 motorcycle collection. He upgraded the front brake to a more powerful Triumph duals leading shoe brake. The sidecar also has its own brake. We have a photo of the previous owner and his wife who rode this rig to the top of Pikes Peak. This machine runs and rides as good as it looks. call John for details 770 447 6945