Squariel

[Greybeard]

British 1932 Ariel Square Four 600cc motorcycle

The Ariel Square Four engine design was the brainchild of Edward Turner, who was managing a London Velocette dealership when he conceived the idea of two parallel-mounted twin-cylinder chain-drive overhead camshaft engines mounted in a common block, joined by a pair of geared flywheels, each mounted on one crankshaft.

Turner first tried to sell his engine idea to BSA; however, they ultimately decided not to use his design. He eventually found interested parties at Ariel, a British small-displacement motorcycle manufacturer that had been producing single and two-cylinder bikes since 1902.

The owner's son, Jack Sangster, hired Turner in 1928, and the first prototype bike appeared in 1930; it had a displacement of 500cc. The first Ariel model 4F or "squariel" bikes, as they came to be known, were sold to the public in 1931, with slightly more than 900 of the 500cc engines manufactured.

Regarded as a touring class bike, the 601cc version of the model 4F was added in 1932. Jack Sangster purchased the ailing company from his father that same year. The increase in displacement aided Ariel in capturing some of the emerging sidecar market, and many U.K. police departments used the 601cc Ariels.

From 1932 to 1940, Ariel built over 2,600 of the 4F 601cc motorcycles. They added a pushrod-design 995cc version, the model 4G, in 1936.

Jack Sangster purchased the motorcycle division of Triumph in 1936 and established the Triumph Engineering Company. He later sold Ariel (in 1944) and Triumph (in 1951) to BSA. The manufacturer continued to market both Ariel and Triumph marques. The 995cc model 4G and 4H Ariels were offered until 1949, with over 4,000 built. The Mk I was released in 1949, and the 995 cc Square Four engine was revised using alloy cylinder heads and crankcases, replacing the previous cast-iron moldings. 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.

https://silodrome.com/history-ariel-square-four/

[Greybeard]

I owned a 4G. I traded it for my A10

[fffcycles]

I have ‘51 4G a’53 MkII, ‘56 VH & NH love them all but ride my BSA’s a lot more.
If my health improves I plan on building up my second ‘48 LS for my good friend Joe to join me on the road.
Frank

[Joolstacho]

They did have cooling issues on the rear pots didn't they. There again it wasn't designed as a 'performance' model. I wonder how they survived in the police.

[fffcycles]

Cooling issue is an urban myth. They just have to be built properly then they are great.  Sometimes a challenge but get it tight and they are a great cruising bike not extremely fast but comfortable