1959 Ariel Square Four MKII
Engine: 997cc air-cooled OHV “square” four, 65mm x 75mm bore and stroke, 7.2:1 compression ratio,42hp @ 5,500rpm (claimed)
Top speed (approx.): 105mph
Carburetion: Single SU, variable choke
Transmission: 4-speed, chain final drive
Electrics: 6v, coil and breaker points distributor ignition
Frame/wheelbase: Single downtube steel cradle/56in (1,422mm)
Suspension: Telescopic forks front, plunger rear
Brakes: 7in (178mm) SLS drum front, 8in (203mm) SLS drum rear
Tires: 3.25 x 19in front, 4 x 18in rear
Weight (wet): 435lb (197kg)
Seat height: 31in (787mm)
Fuel capacity: 6gal (22.7ltr)
Price then/now: $950 (est.)/$12,000-$33,000
Back in the free spirit heyday of the 1960s and 1970s referring to something as “square” was a put-down. Square was a term used to denigrate the straight-edged conformist establishment, and if you were labeled square you certainly weren’t “with it.”
When Wisconsin adopted a helmet law in 1968 many didn’t appreciate being told by those in power what they could and could not do. One of them was Bill Schertzl of Eagle River, Wisconsin. Bill was a long-haired free-spirited individual, and together with several of his like-minded friends, they protested the law. Eventually, on March 3, 1978, the Wisconsin helmet law was repealed and it was declared that only those under the age of 17 had to wear a lid.
That meant Bill and his friends could ride with the wind fully in their hair. But what is incongruent with Bill and his anti-establishment attitude is his motorcycle of choice happened to be an Ariel Square Four.
And not just one Square Four. In the 1970s he had several, including a chopper and a couple of nice, tastefully chromed out originals. He rode them regularly, but over time they ended up parked in his garage and eventually had to be sold off. That’s when, two years ago, Jim Balestrieri of Elkhart Lake, Wisconsin, heard about the collection.
Jim is an enthusiast who began riding motorcycles in the late 1960s with his junior high school friends, and Hondas were their chosen machines. He started out on a 305 Scrambler and ended up in the mid-1970s on a Gold Wing. Jim rode until 1984, when he opened his business, got out of motorcycles, and began club racing automobiles.
His wife, he says, then made the mistake of buying him a copy of Hugo Wilson’s TheEncyclopedia of the Motorcycle. Flipping through the pages and seeing all of the interesting historical machines, Jim decided he’d begin collecting with the intention of one day opening a motorcycle museum.
That dream became a reality in 2017 when Jim and lifelong friend Tom Kostrivas opened Throttlestop in Elkhart Lake, Wisconsin. There, together with general manager Nic Piekarski, the team buys, sells, consigns and stores exotic cars and also runs a detailing department. Jim placed his motorcycle museum in a separate building on the Throttlestop property which now displays more than 40 machines, from a 1914 Indian V-twin board track racer to a 1961 Triumph 3TA, a 1975 Suzuki RE5 and even a 2006 Harley-Davidson VRXSE Screamin’ Eagle V-Rod Destroyer drag racer.
At Jim’s “regular job” in human services, Jim has a coworker who is Bill’s nephew. One day at the office he mentioned his uncle’s cache of motorcycles. That was enough to pique Jim’s interest, and he went to view the contents of Bill’s garage. Jim ended up buying a Suzuki RE5, a 1957 Ariel Square Four chopper and 1955, 1958 and 1959 Square Fours.
From the beginning
The history of Ariel dates back to 1869 when James Starley, an engineer with the Coventry Sewing Machine Co. of Birmingham, England, thought two-wheeled transportation held some promise. In 1870 he and his partner William Hillman built a high-wheel bicycle and chose to name their company Ariel, a nod to the flying spirit from Shakespeare’s play The Tempest. Like many other British manufacturers that started out with bicycles, powered cycles soon followed. Ariel built a motorized three-wheeler in the late 1800s, and their first motorcycle in 1902.
By 1928 it was Jack Sangster who was managing Ariel and he hired aspiring motorcycle engineer Edward Turner. Turner had been working at a motorcycle shop in Peckham, England, and while there he had built his own single-cylinder overhead cam motorcycle engines and drawn up plans for a 4-cylinder powerplant. He’d been shopping his designs around to various English motorcycle manufacturers, including BSA, who showed some initial interest in his singles, but nothing became of the discussion.
That’s when Turner turned up at Ariel. Instead of the singles, Sangster and Ariel designer Valentine Page were captivated by Turner’s 4-cylinder design. Turner began working at Ariel under Page, and he was joined by Bert Hopwood. They worked on Turner’s design that held four pistons in a square layout, with fore and aft crankshafts geared together.
According to Roy Bacon in his book, Ariel: The Postwar Models, the square four layout “… offered the same good balance as the in-line (4-cylinder engine) plus very compact dimensions, while the four small even power pulses of the cylinders was far less destructive than the one thump of a single.”
“As originally schemed by Turner,” Bacon continues, “the Square 4 engine was undoubtedly light and compact, being made more so by the use of a 3-speed gearbox built in unit with the engine. He coupled the two crankshafts together by cutting (helical) gear teeth on the central flywheel each had, and the rear one drove the gearbox. So small and light was the assembly that it could, and did, fit into the 250 frame (Ariel’s 250cc Colt model had a forward-canted cylinder and head, which protruded between widely splayed front frame downtubes) giving a very light motorcycle.”
However, what finally entered production in 1930 wasn’t Turner’s initial vision. Inadequate cylinder head finning of the original design resulted in cooling problems, and the unit-construction layout would have been too costly for full-scale production. Ariel instead built a 498cc 4-cylinder engine with chain-driven overhead camshaft and separate Burman gearbox. The four’s crankcase fit neatly between the splayed downtubes of Ariel’s SG31 500cc sloper rigid frame, which meant something of a weight penalty. Gas tank, girder fork, wheels and brakes were shared between the two models. Late in 1930 at the Olympia Motorcycle show in London, England, the brand-new Ariel Square Four was launched for the 1931 model year.
The machine met with success. During the 1930 London to Land’s End Trial the Square Four placed first. Ariel increased the four’s sidecar-hauling capability in 1932 when capacity was taken to 601cc. Ariel sold both the 500 and 600 Square Fours until 1933, when only the 600 was available.
The Square Four was significantly revised for 1937 when the company offered the 600cc 4F and the new 1,000cc 4G. On both models, the engine had been completely redesigned and the overhead cam was gone, replaced by a centrally located cam in the center of the crankcase — which was now split vertically as opposed to horizontally. Short pushrods operated the overhead valves and the crankshaft coupling gears moved from inside the case to outside and were located under a left side cover. The cylinder barrel and the 12-stud head were cast iron but the rockers were maintained in a separate alloy top chest.
Focusing on the larger engine, bore and stroke was 65mm by 75mm for a displacement of 995cc with a 5.8:1 compression ratio. In 1939, Ariel listed the Square Four De Luxe 1,000cc Model 4G together with a Square Four Standard 1,000cc Model 4H, and the smaller 600cc 4F. The De Luxe model featured fishtail mufflers, chromed and pinstriped rims, a quickly detachable rear wheel and a larger gas tank. The De Luxe was also equipped with a sidestand. New for 1939 was Ariel’s spring frame, essentially a plunger-style rear suspension that could be ordered, at extra cost, to fit any of the Square Four models.
The next version
During the war years, Ariel quit civilian production and focused on constructing single-cylinder machines for the military. When the factory resumed regular production in 1945 the only Square Four model in the lineup was the 1,000cc 4G, updated in 1946 with telescopic forks.
Ariel shed some weight from the Four’s powerplant in 1949, replacing the cast iron cylinder block and head with all-alloy components for the Mark I Square Four. The Lucas magdyno unit was switched to coil ignition and a 70-watt dynamo with a car-type distributor was driven by skew gear. On the timing cover, the inscription changed from “1000” to “Square Four” and in 1950 the speedometer was relocated from the tank-top instrument panel to the fork top. By 1951, the tank-top panel was gone in its entirety and the Smiths speedometer was housed in an alloy casting that doubled as the upper fork triple tree.
The next update of the Square Four happened in 1953 when Ariel began selling the Mark II model, instantly recognizable thanks to its distinctive four separate exhaust headers. In 1954, the sprung solo saddle was replaced by a long bench-type seat but the plunger rear suspension remained. Over the next five years, changes were limited in 1956 to a hooded headlight and fork cover featuring a top panel with speedo, ammeter and light switch. At the lower end of the fork was a new full-width light alloy hub with 7-inch brake. Rear suspension was still provided by the plunger frame, and that remained until the end of the line with the 1959 model — when Ariel suspended all 4-stroke motorcycle production to focus on 2-strokes.
Back in Wisconsin
After Jim acquired the Ariels he showed off the Square Four chopper at a Mama Tried event in Milwaukee. The rest of them were cleaned up and while Jim thought about leaving the bikes alone, the 9 model was important to him.
To see a walk-around video of our feature Ariel, go to bit.ly/square-four
“There were two things about that one,” he explains. “It was a unique color known as Cherokee Red, and from the information we could dig up, it was built March 24, 1959, and it could be one of the last Square Fours to leave the factory.”
Jim turned to Brady Ingelse of Retrospeed in Belgium, Wisconsin, for some input.
“I first met Brady at a Road America event and saw his company’s restorations there. That’s when I said this is a guy I’ve got to get to know,” Jim says. Initially, they both thought a sympathetic restoration of the ’59 would suffice. Brady took delivery and first ensured the Square Four would run. It would, and while the engine sounded okay, as technician Ryan Luft took the lead on the Ariel and began to work on the project, it became apparent the motorcycle would require a complete rebuild.
The red paint was flaking off the chrome on the gas tank, but much more seriously, the valve guides simply fell out of the head when it was turned upside down. At that point, Jim and Brady agreed everything needed to come apart to the last nut and bolt.
From the bottom up
Starting with the engine, to ensure the crankshafts were serviceable and crack-free they were magnafluxed. Thankfully, they were in good condition. After Ryan cleaned up the cases, every bearing and bushing was replaced. Retrospeed turned to their friend Dave Murre for much of the specialized machine work.
“Not only is Dave a machinist, but he’s a machinist who can’t stop talking about motorcycles, and especially British machines,” Brady says. “He gets it.”Dave machined Kibblewhite nickel bronze valve guides meant to fit a Triumph twin to suit the Ariel’s head and made a new seal carrier — to hold a Honda seal — for the output shaft of the transmission.
Draganfly Motorcycles in England (draganfly.co.uk) was able to supply a good portion of the required parts, including a complete new exhaust system with mufflers. Most of the pieces that could be chromed, including the dent-free gas tank and parts such as the handlebars and clutch cover were dipped at the Chrome Shop Inc. in Menasha, Wisconsin. However, there was more chrome to remove from parts of the Ariel that were never meant to be plated.
“This bike was littered with extra chrome plating,” Brady tells us. Examples of that include the engine mounting plates, rear stand and spring, fender brackets and many smaller pieces. “That makes it difficult to know exactly how it left the factory, and we did plenty of research to ensure everything was correctly painted, chrome plated, or cadmium plated.”
After completing many spray-outs to ensure a match to the Cherokee Red paint, the frame, fork sliders and upper covers, engine mounting plates, headlight nacelle, taillight housing, oil tank, tool box and stands were sprayed by CG Collision in Belgium, Wisconsin. They were also able to successfully mask and paint over the freshly chromed gas tank, a job that sets the entire motorcycle apart from many other machines.
With the Ariel together and painstakingly prepared to ensure there would be no static oil leaks, Ryan says he steeped himself in how to properly set the timing on the Lucas distributor that sees one set of points providing sparks to the four plugs and how to tune the SU carburetor. All dialed in with just over 30 miles on the odometer accrued during shakedown runs, Ryan says the Square Four is one of the easiest-starting motorcycles he’s ever worked on.
“It’s unreal,” he says. “Turn the key, flip a lever on the carb and give it one kick and it fires right up.”
And that, right there, is proof that it’s hip to be square. MC
- 1 year of Motorcycle Classics magazine both print and digital – six premium issues full of exciting and evocative articles and photographs of the most brilliant, unusual and popular motorcycles ever made!
- Special discounted prices on books, t-shirts, and archive products in the Motorcycle Classics Store
- Online access to Motorcycle Classics content dating back to 2005
- Access to exclusive online content - restoration projects, rides & destinations, and gear reviews.