The Ariel Square Four design goes all the way back to 1931, soon after Edward Turner designed an interesting new four-cylinder motorcycle engine formed from two OHC parallel twins. The design became known as the square four engine, and lent its name to this Ariel motorcycle. Turner had actually shopped his engine design out to other British firms, but BSA rejected it. The bike was produced until 1959, making this example one of the last few out of the factory.
By 1953, the Ariel Square Four had already gone through a few revisions, and was formally known as the Mark II. The Mark II featured a 997 cc engine. Upgrades to the powerplant included separate barrels, a new cylinder head, and four exhaust pipes, which bumped up horsepower to 40. This enabled the Square Four to ‘do the ton’, even with a curb weight of 425 pounds.
This specific Ariel Square Four (VIN: GM804) is an older restoration (10-12 years ago) that still looks good. The fuel system was recently cleaned and had some parts replaced, and there are “probably” less than 500 miles on the bike since the restoration. Everything works, though the seller recommends that the tires be replaced due to dry rot and cracking before you ride the bike. The reserve has been met, so this bike will be going to a new owner – though the bidding is already quite high!
Find this Ariel Square Four for sale in Costa Mesa, California with bidding up to $23,499
