Known as one of the most glamorous British motorcycles, the Square Four was in production for Ariel’s range of motorcycles for over 27 years. The engine was designed by Edward Turner, a young engineer who later became the boss of Triumph. The Square Four design came from Turner, who initially sketched it onto the back of a cigarette packet as an idea, before offering it to different motorcycle manufacturers.
It was Ariel who took him and his engine design on, and the first to be launched was the 500cc in 1930, followed by a 600cc two years later. The design had many problems, mainly overheating. The problems were addressed by Val Page, who was also famous within the industry, and they modified the 600cc and launched the larger 1000cc.
Production was stopped due to World War II, but restarted in 1945, with the new bike like the one we have here, featuring telescopic forks and the new 1000cc engine.
The 1951 Ariel Square four was found in the USA, where it had already been restored to a high standard, as you can see from some of the photographs that came with the bike. The restoration included a full strip down and rebuild, including the engine. It was imported back to the UK on the 15th May 1991.
The seller purchased the bike shortly after spotting it for sale 4 years ago, when a touch of nostalgia kicked in, with memories from his travels, usually going on holiday either on the back or in the sidecar of his dad's Square four, which was even known to have had a trailer attached, along with the sidecar!
With these memories, the seller knew he had to have it, and add it to his lovely collection of classic bikes. A move to warmer climates has brought on the sale of his much loved Ariel Square Four.
The V5 is present and shows 2 previous keepers since the registration of the bike on 30th April 2008. There is an import certificate showing the bike actually came into the country on 15th May 1991, through East Midlands Airport.
There are a few invoices for some odd parts over the years, and some old MOT certificates from around 2008.
This 1951 Ariel Square Four 1000cc, was restored in the early 90’s, and since then it looks to have been well cared for and maintained to a high standard. Starting at the front of the Ariel, the mudguard is in good order, with just a small chip on the front edge. The bottom is free from any corrosion.
The headlight works as it should and has a built-in amperes gauge which is reported to be working as it should. The handle bars are in good order with no or little corrosion to be seen to them or the mirrors. The odometer is showing a reading of 20,995 miles.
The frame and forks look to have been powder coated in black for a strong durable finish. Sitting at the top, the fuel tank has been finished with a gold pinstripe and then lacquered over for a smooth finish. The oil pressure gauge is working correctly and there are the Ariel pads mounted to the sides for added comfort.
The sprung seat has some light signs of wear to the edges but nothing too excessive, and would be quite easy to get recovered should you wish. With the option for a pillion passenger there is a seat mounted to the mudguard and some fold away footrests, and like the front, the rear mudguard is in good condition.
The chrome wheels look to be in really good condition with a nice bright finish, and the centres have been painted with the same colour scheme as the fuel tank.
The Square Four is a 1000cc 4-cylinder engine, capable of pushing the Ariel to near 100 mph. As mentioned, there are photographs with the engine stripped down for the rebuild when the bike was restored.
The Ariel starts and runs as it should, and the ride is smooth from the punchy 1000cc engine. The seller reports that the bike changes gear as it should and the brakes bring the bike to a stop with ease.
Since owning the bike, the seller has only used it for a few short runs to local shows, but does mention that it rides superbly and is a nice bike to take on a long cruise.
With one of the most innovative engine designs of the time, the Square Four 1000cc is a joy to own. The engine produces a healthy punch from low down revs and a generous mid range torque, giving you ample acceleration for overtaking, or, as often seen, pulling a sidecar.
A nice machine to have in the garage for when the mood takes you, or something to use on a more regular basis. Being one of the most sophisticated British bikes of its time, the Ariel offers nice performance and good reliability.
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