Category: Ariel

Sophisticated Performer: 1957 Ariel Square Four for Sale

1957 Ariel Square Four L Side

A vintage luxury sports machine, the Ariel Square Four had, as the name suggests, four whole cylinders at a time when most motorcycles of the period had just one or two. Automobile components can get away with being heavy, but over-engineered solutions in a motorcycle application mean significantly reduced performance and, for years, four-cylinder engines weren’t compatible with twin demands of light weight and reliability. Inline fours can be tricky to package into a motorcycle, particularly when configured longitudinally, as was common before the Honda CB750. But the Ariel uses an interesting “square” format that features a pair of parallel twins, complete with a crankshaft for each. Not only did this solution offer up the power and smoothness of an inline four, the very compact design meant it could be squeezed into existing frames meant to house a parallel twin. No surprise, as the design was originally intended for BSA.

1957 Ariel Square Four R Side Rear

The first generation of Square Four displaced 500cc with a bump to 601 for increased torque, so riders using the bike as practical transport could more easily drag the weight of a sidecar around. That early overhead cam design had issues with overheating, as the square four configuration naturally has a hard time getting cooling air to the rear pair of cylinders. Suzuki’s later RG500 engine used liquid-cooling to get around this problem, but that was obviously not an option here.

1957 Ariel Square Four Dash

The engine saw a complete overhaul in 1937 with a shift from overhead cams to cam-in-block and pushrods, but a big jump in displacement to 997cc.  In 1949, the iron head became aluminum for a huge savings in weight and the version seen here is the final iteration, with four individual exhaust pipes, instead of the earlier pair of siamesed parts that make the bike look like it’s powered by a bulky parallel twin.

1957 Ariel Square Four Engine

From the original eBay listing: 1957 Ariel Square Four for Sale

Up for sale is a restored Ariel Sq4 This bike was completely restored 10 years ago and sat in a collection for 5 years.  I bought it and meet the person who restored it in Mass. He is good at what he does and the bike still shows very well. All the miles were put on by me, last being a 50 mile ride 2 years ago. The bike has been started and ran in the last few months. It will start right up and operate very smooth. There are no known problems. The restoration was both mechanical and cosmetic at the time. Buyer will be responsible for transportation from Pgh PA.

I’m assuming “Pgh” is Pittsburgh in this case. There’s very little time on this auction, with bidding up just north of $16,000 and the reserve not yet met.

1957 Ariel Square Four Tank

So what’ll she do, mister? Well that nearly full liter of displacement gave 45hp and the bike weighed a surprisingly svelte 425lbs, so the Square Four could very nearly “do the ton.” But while bikes like the BSA Gold Star were about ultimate performance, the Square Four was about the way in which it delivered that performance, and the smooth relaxed power and sophistication was really in a class by itself from the bike’s introduction in 1931 until it was discontinued in 1959, a remarkable production run for any motorcycle.


1957 Ariel Square Four R Side

Hip to Be Square: 1951 Ariel Square Four

1951 Ariel Square Four L Front

By the 1970s, four-cylinder powerplants were dime-a-dozen in the motorcycling world. Formerly found only in high-end exotic machines like this Ariel Square Four, they’d become a characteristic of the generic “Universal Japanese Motorcycle.” But in the 1950s, a four-cylinder engine was something to brag about.

These days, inline and V4 configurations are common, but the Ariel used an unusual “square” configuration not often seen outside two-stroke race-replicas like the Suzuki RG500 Gamma. As you’d expect, the square four is really a pair of parallel-twins, each with its own crankshaft, geared together and sharing a head. This makes for a compact motor that slotted easily into existing frames, but one with the inherent cooling problems that result from limited airflow to the rear cylinders.

1951 Ariel Square Four R Engine

Introduced in 1931, the engine was significantly overhauled in 1937: in a seeming step backwards overhead cams were changed to pushrods, but the heads and barrels were changed from iron to aluminum and displacement increased significantly from 500cc’s to almost 1000. Reliability was increased and the character suited the bike’s mission: while performance was impressive with over 90mph possible, it was smooth and very torquey, a “gentleman’s express.” Production continued until 1959.

1951 Ariel Square Four R Rear

Today’s example looks to be in very nice cosmetic condition, but has been off the road for a while and will need some work to set it right.

From the original Craigslist post: 1951 Ariel Square Four for Sale 

You won’t see one like this every day… A MAGNIFICENT 1951 Ariel Square four 1000cc with a 1954 engine (four pipe manifold). Check the photos. One of the world’s best motorcycles ever from that decade. Much in the way of papers, manuals and history information available. After its long rest it will require some freshening before an outing, but it’s all do’able. The price has been reduced to $16300. Call for further information and an appointment to view.

This vehicle is currently Cal licensed , clear titled, and on non-op status.

The seller is asking a bit less than I’ve seen for nice Square Fours recently, and the mention of it being “reduced” suggests that interest has been low. I’m wondering if the updated engine is causing issues for fans of originality, or if the possible headache of getting this bike on the road is putting buyers off. The seller doesn’t mention why the change to the later powerplant was made, but certainly the performance benefits should be worth the update for fans of function, and the later exhaust manifold shows off the bike’s four-cylinder-ness proudly, whereas the original could be mistaken for a big parallel twin. The seller also doesn’t mention exactly what it might need, if anything other than usual, to get it back on the road as “its long rest” isn’t really quantified, but cosmetically, the bike appears to be complete and in good shape.


1951 Ariel Square Four Front

Sophisticated Vintage Brit: 1952 Ariel Square Four for Sale

1952 Ariel Square Four R Front

The motorcycling industry prior to the 1960’s was centered on single and twin-cylinder machines, and, at a time when simplicity equaled reliability, Edward Turner’s compact four-cylinder design would have seemed extremely exotic. Prior to the Lancia Aurelia’s introduction in 1950, car and motorcycle engines used “inline” formats almost exclusively, and although inline fours work fine in automotive applications, they can cause packaging, as well as cooling, problems in motorcycles.

Originally rejected by BSA, the unusual square-four design found a home with Ariel and featured a pair of parallel twin blocks siamesed with their transversely-mounted cranks geared together and sharing a common head with overhead cams. This compact design allowed a four-cylinder powerplant to be fitted in to frames that were normally home to engines with one or two cylinders.

1952 Ariel Square Four L Rear

The original 500cc engine was eventually enlarged to 601cc’s to increase torque for riders who wanted to fit a sidecar to their machines, but the OHC design had a propensity for overheating the rear pair of cylinders, as cooling airflow was blocked by the front pair.

1952 Ariel Square Four R Front Engine

The engine was completely redesigned in 1937 with pushrod-operated overhead valves and a big displacement increase to 997cc’s. Aluminum replaced iron in the head and cylinders in 1949 for a significant savings in weight, and the final iteration of the engine introduced in 1953 was distinguished by four separate exhaust pipes exiting the head, although this example is the earlier, two-pipe version.

1952 Ariel Square Four Dash

From the original eBay listing: 1952 Ariel Square Four for Sale

An English country cruiser capable of 100mph….

Gaining popularity as “the poor man’s Vincent”, the Square 4 is steadily increasing in value.

The current owner is the fifth (first not named David) in a line that traces this 52 Ariel Square 4 Mk I’s origin to New Jersey; where it was purchased new in 1952.

The most recent previous owner bought the bike while on a trip in N.Y. State in 1996. After the purchase he had a full restoration performed prior to displaying in his collection.

Upon receiving the machine, the current owner kicked it over twice and it started right up and ran nicely. He rode it around his neighborhood for an hour, and then carefully decommissioned the Ariel for display in his collection.

The odometer shows 56,818 km or 35,305 miles.  The current owner has done a fair bit of detail work on the machine since acquiring it – much polishing, inspecting, cleaning and servicing inside external cases etc. He removed and cleaned the oil tank & lines and installed a rebuilt exchange oil pump from Dragonfly.

The frame is refinished but not powder coated and makes it look very authentic. The tins are all superb in that they are original but refinished beautifully and correctly. Chrome is all perfect.

All of the wiring was redone correctly and everything works. Even the tiny light in the speedo and the brake light. (all the lights work in other words)  The bike includes the original ignition key and the (optional?) jiffy side stand.

The owner is in possession of a dating certificate with an extract from the Ariel Works Ltd. despatch record books confirming that all of the major components on the machine are original. With the exception of perhaps the rims, tires, spokes and buddy pad this bike has all of its original pieces, nicely and carefully restored.

Also included in the sale are the original owner’s manual signed by the first two owners and a copy of the 1970 NY State vehicle registration bearing the name and signature of the second owner who purchased the bike from his friend and original owner in 1957.

1952 Ariel Square Four R Rear2

Weight was relatively low for such a complex machine and the bike could top 90mph, no small feat in 1950, although maximum performance wasn’t really the point, since lighter, simpler singles like the BSA Gold Star could match those numbers. It was the square four’s smoothness and sophistication no twin or single could possibly match that was the source of the bike’s lasting appeal, with production lasting from 1931 until 1959.

1952 Ariel Square Four L Tank

This example is in excellent condition and appears to be well-documented. Bidding is north of $22,000 with plenty of time left on the auction. The popularity of some bikes will naturally rise and fall with prevailing trends, but Square Fours have been steadily appreciating in value for some time now, and looking at this bike, it’s easy to see why.


1952 Ariel Square Four L Side

1956 Ariel Square Four for Sale

1956 Ariel Square Four R Front

Motorcyclists are often lone wolves, men and women of few words, rugged, independent folk for whom actions speak louder than words. Like the seller of this tasty classic Ariel Square Four.

From the original eBay listing: 1956 Ariel Square Four for Sale

1956 Ariel square 4 runs great, starts first kick. Everything on the bike works well. It does need front fork seals they are leaking a bit.

It comes with a clear Texas title. Please ask questions

That’s it, the whole listing. Luckily, the photographs are bright and clear and show a bike in very nice condition. I’d love to know a bit about this bike’s history, updates and maintenance that have been done. I guess the seller figures prospective buyers already know all about these. In case you don’t I’ll fill you in a bit.

Produced between 1931 and 1959, Ariel’s Square Four began as a 500cc machine and ultimately grew to the 997cc machine you see here. Weighing in at a relatively light 425 pounds and producing 45bhp it can easily keep up with modern traffic, although limited cornering clearance and period brakes mean you should plan your maneuvers well in advance. While it isn’t necessarily much faster than some of the bigger twins and singles of the period, the four was obviously smoother with a wider spread of power.

1956 Ariel Square Four R Rear

Keep in mind that four cylinder motors were considered very exotic until Honda and Kawasaki flooded the market with them in the early 1970’s. Twins and singles ruled the motorcycle world for the most part, and the square four was a way to introduce the smoothness and power of a four into existing frames originally designed to hold singles.

Like the square four two-stroke race replicas of the 1980’s, the Ariel is quite simply two parallel twins with their cranks geared together sharing a single head. Early bikes tended to overheat the rear cylinders, as you might expect, since they were blocked from receiving any cooling airflow. Later revisions to the bike addressed this, although it was always a weakness of the design.

1956 Ariel Square Four L Front

The later examples were known as “four pipe” bikes for obvious reasons: note the four separate exhaust pipes coming out of the head. In addition, the Mark II redesign featured extensive use of aluminum for the block and head, saving 30lbs over the earlier models.

The buy it now price is set at $21,000 which pretty big money. Ebay indicates several offers have been made, but I’d expect they were pretty far off the asking price, which seems a bit steep, even for a bike this nice.


1956 Ariel Square Four L Rear

Don’t be an Ariel Square Four man.

Ariel got it’s name from a Shakespeare’s play “The Tempest”. Shakespeare’s Character was a airy spirit based on a messenger of the gods, Mercury. The company started with bicycles like a lot of other motorcycle manufacturers. One of the things that set them apart is that they made a motorized tricycle in 1898. I’d like to see one of those some day, sounds cool. In 1901 their first motorcycle was released it had a 211cc engine. They moved onto big singles and V-twins. Then in 1931 a 500cc square four was introduced. By the late 1930’s they had released a 1000cc square four. In 1953 they went to a four pipe square four. The bike you see here is a two pipe sq 4. A very unusual engine design with two cranks connected by a gear. This bike has a neat story of procurement from the seller. I like to here about bikes being taken down from the rafters and put back on the road.

1950 Ariel Square 4 For Sale on eBay

From the seller:

1950 Ariel Square 4 in excellent condition and with only 15,293 miles. Absolutely lovely bike, starts on the first kick, and rides perfectly. The 1000cc 4-cylinder engine is factory stock with no mods. Turn on the key, pull the choke, and starts easily on the first kick. Settles into a smooth quiet idle but has a very unique exhaust note that sounds like a V8 that snarls with revs above midrange (I’ve read that the sound is reminiscent of an Offenhauser racing engine). These are unusual engines; basically two vertical twins in one square block, with two separate crankshafts connected together with a large gear. Just rebuilt by Bancroft Vintage Motorworks; runs perfectly and without issue; no leaks, no noises. The 4-speed transmission shifts perfectly and the factory gearing allows relaxed 60 mph cruising while providing strong acceleration. Very pleasant bikes to ride; draws much interest at shows & bike night  events. The headlight (high & low beam), tail light, brake light, and horn all work properly and the speedometer is accurate. Perfect chrome gas tank with red & gold trim. Perfect black lacquer forks, frame, and fenders. The original decals from Ariel are still in place and the original dealer’s sticker (Johnson Motors on West Pico Blvd in Los Angeles, California) is still on the rear fender. There is no rust. Perfect original exhaust & mufflers. Perfect chrome spoke wheels fitted with Dunlop tires. Incredibly nice bike.

Note: I found this bike suspended from the ceiling over the bar in an Ohio restaurant, being used as a display. After much wrangling with the owner (who subsequently wanted my Velocette), I bought and brought it to Bancroft Vintage Motorworks since, although in perfect cosmetic condition, the bike had not been started or ridden in a few years. Mr. Bancroft disassembled & rebuilt the engine, repaired the electrical wiring, and went through the bike. A new battery, engine rebuild, carb rebuild, valve job, all new seals, all new fluids, and complete tune-up later, it started on the first kick and rode perfectly down the road. It now is fully road ready and will win trophies at virtually any show entered. It is still every bit a museum quality show bike but also a very capable rider as well. Gorgeous.

See additional full-screen size photos and other interesting vintage bikes at

This a very fine example of people trying new things to make their mark. The sq 4 has unique looks, sound and performance. I tend to like the unusual, it reminds me of a saying I heard somewhere, “if a bunch of people tell you it won’t work then your onto something special”. Sometimes they’re right and sometimes you leave a bookmark in history. Edward Turners 500cc OHC sq 4 left a mark that’s for sure.


1955 Ariel VH HS 500

When people see the four letters, I, S, D, T together, they have no idea what they mean. Some will know that Steve McQueen rode some Triumphs for the United States in something called ISDT. Very few will know that they stand for International Six Day Trials, and understand that these six days of off road competitions are the beginning of motocross that we know today. But just like email compared to snail mail, people use to take a lot longer to figure out who was the best rider on the best machine. This 1955 Ariel VH HS ISDT would be a very good bike if you wanted to spend 6 days in the woods of Europe.

From the seller

This is a unique opportunity to acquire a very special Ariel.  First registered in 1955 as a Ariel VH 500 with a sidecar, it was reportedly fitted with an all alloy HS Mk1 engine by UK ISDT and trials rider James Sandiford (later to become the UK Montesa importer) and ridden in competition.  Later in its life it was owned by 2 time European MX champion Dave Bickers (Mr. Bickers has confirmed this to be true) and he has signed the gas tank, as has arch rival and good friend Jeff Smith (see youtube video of a classic battle between these two at the grandstand scramble).  The bike was then rebuilt in the UK before coming to the USA.  The bike is presented in full International Six Days Trials trim, and has many special features including front fender nail catcher, air bottle for puncture repair, spare cables in place for quick change, easy roll on center stand, tank tool bag, BSA seat fitted to allow for easier footing (lower than stock Ariel seat), competition mag/dyno, high level tucked in exhaust, large air cleaner assembly and wide ratio transmission.  The bike runs well and all electrics work including horn and brake light.  The bike is very nice but not mint, it may be seen and ridden prior to auction end with appointment.

Motorcycles were first developed before there were real roads, so every rider had to be able to negotiate the craters in the road, gravel, and mud during the rainy days. The ISDT was a competition in which riders spend 6 days looking for the worst of the roads, in every country in Europe. As the seller points out, the bikes were close to stock, with additions of power because it was a race, but also special equipment to deal with road hazards.

In today’s motor cross competitions its all about the big jumps, 100 feet into the air, and 10 minutes of hang time. During simpler times, a National team of riders would set off and follow the map which took them over hill and dale. You would need to repair punctures, so an air bottle was needed. Knobby tires, and maybe and inch or two more travel in the suspension appear to be the only concessions given to stock road bikes. Today, these might be considered a flat tracker, but the coarse they raced on was anything but flat.

Flipping through the channels late at night I saw a race sponsored by an Austrian energy drink that might be as close to compare to the ISDT that this 1955 Areil raced in. But the cliff faces, and drop offs that today’s riders are able to do would destroy a bike from the ISDT days. There are still vintage race series that you could compete in. Of you could just take it out for coffee, or to work every day. BB

1936 Ariel Red Hunter

I have never learned a lot about Ariel Motorcycles, but I have always liked them. This Red Hunter from 1936 offered up on eBay now is the single cylinder from the company that started making powered bicycles in 1898. The singles came in 250cc, 350cc and the big 500cc and were popular for both grass track racing and trials competitions. The Red tank and rims are obvious highlights to this big British single, an advertisement as it goes down the road.

The seller tells very little about the bike

Motor number CB2815

Frame F4674

Reserve less then the Buy it now $14k

One of only 10 Bronze Head versions

An eBay shopper corrected the seller on the year of the bike, and I would be surprised at the limited number of Bronze Cylinder head examples listed by the seller. Before aluminum found itself into cylinder head, bronze was a performance upgrade that you would see in competition bikes. Even thought bronze was not an improvement in weight, it did give better thermal conductivity, dissipating heat from exhaust valves and valve springs who’s metallurgy was not yet up to the wear and tear of competition. As you can see the valves are un-covered, allowing the rider to quickly remove and replace broken valve springs.

The Red Hunter was offered from 1932 through 1959. The engine was designed by Val Paige who had come from J.A Prestwick, and improved upon by Edward Turner who would become an icon for anyone who rides a Triumph. The girder forks up front and rigid rear end did not stop riders from taking these bike off road in trials events, and the high exhaust pipe, and bronze head lead you to believe that this bike was special ordered to compete. Number I found give the 500cc engine 17hp at 5600rpm and a top speed of 80mph. This may not seem a lot, but you have to remember that the speed limit in England was 30mph for many years.

Ariel was bough by BSA after WW II and like other names purchased by what would become AMC, the Ariel did not gets its opportunity to fight for market share. They went through a period when the badge found itself on scooters and not motorcycles. Which is too bad because with designers like Val Paige and Edward Turner the Ariel had what it takes to compete. This Red Hunter is proof of that.