Unbelievably, some people think multis are contemporary platforms that arrived, just recently, from the East. This is a look back at some important four-pot trail blazers.
The Time of the Four-Fathers
Before Honda’s 750-Four of 1969 re-wrote the book, a four-cylinder engine in a motorcycle was considered somewhat extravagant, the preserve either of the racetrack or of spendy, top-of-the-range tourers. Few manufacturers made them, and they generally fell out of favour after WWII: the last pre-Honda four-cylinder bikes commercially available (the custom Munch Mammoth notwithstanding) were the Nimbus, last produced in Denmark in 1958, and the Ariel Square Four, which lasted until 1959.
The four-pot plot has its origins in the first decade of the 20th century. In Britain, the Wilkinson Company (of sword and razor blade fame) manufactured the elegant but cumbersome Touring Auto Car and the equally unwieldy Touring Motor Cycle, both more like a La-Z-Boy on wheels. In Belgium, Paul Kelecom of famous arms manufacturer FN designed an in-line four, inlet-over-exhaust engine of just 363cc that nevertheless powered to third place in the 1908 Isle of Man TT (multi-cylinder class) with Mr. R. O. Clark at the controls. Production of the FN four ran from 1904 to 1926.
It’s said that Peder Anders Fisker of Denmark’s Fisker & Nielsen company took his inspiration from FN in creating his four-cylinder Kokkenror (“Stovepipe”) Nimbus of 1917. This featured a tubular spine fame and swinging arm rear suspension, both very advanced for the era. The company took its time with a replacement for the Stovepipe, which finished production in 1928, unveiling the MkII in 1934. This is the better-known Nimbus, with its riveted strip-steel frame, rigid rear end with shaft drive, and telescopic fork.
The 750cc OHV engine had exposed valves and just two main bearings: performance was limited by crankshaft whip and severe overheating if the available 22 hp was used in earnest. Nevertheless, the MkII remained in production from 1934 to 1958 with almost no changes, and found roles in military and police forces. Only around 12,000 were built.
William Henderson was a committed four-cylinder man. He designed his first quad for the company he and his brother Tom established in 1912. Started with a cranking handle, the 965cc inlet-over-exhaust (“F” head) engine used three main bearings, and drove the rear wheel by chain. A Henderson circled the globe in 1912—the first two-wheeler to do so. Henderson’s next innovation was a two-speed rear hub, with a capacity increase to 1064cc for 1913, and a three-speed gearbox in 1917.
That year, the Henderson brothers sold out to Ignaz Schwinn’s Excelsior Company, though they stayed on with the new owner until 1919. The Model K Excelsior-Henderson of 1920 appeared with side valves for both inlet and exhaust, and the drivetrain fitted into a new heavier frame and fork. A good seller, the Excelsior’s last major change was a new five-main-bearing, inlet-over-exhaust engine for 1929 before the canny Schwinn, anticipating a lengthy depression, pulled the plug on motorcycle production to focus on bicycles.
The Henderson brothers, meanwhile, were back in business on their own, producing the Ace Four for 1920. This followed Henderson’s earlier design of IOE valves, three-speed gearbox and chain final drive, but was now 1220cc. It was an Ace Four that Erwin “Cannonball” Baker rode on his record-setting ride from Los Angeles to New York in 1922. Sadly, William Henderson was killed while road testing the Ace, and in spite of the highly acclaimed Four setting numerous speed records, the comp
any foundered in 1924. Eventually in 1927, Indian snapped up the company together with its chief engineer, Arthur O. Lemon.
Indian moved production of the Four to Springfield, producing the Indian-Ace for one year before replacing it with the Indian 401, followed by the five-main-bearing 402 for 1929. By 1930 the Four had adopted more Indian practice, including a frame adapted from the 101 Scout, and Indian’s trademark trailing-link, quarter-elliptic leaf-spring front end.
An oddity was the “upside-down” Indian Four of 1936-7, with exhaust-over-inlet valve gear, putting the exhaust at the top of the engine with the carburetor below. Though the EOI proved efficient, excessive heat (which toasted the rider’s nether regions) and increased maintenance were persistent issues, and the IOE format returned for 1938. Production of the Four, by then with the Chief’s full-skirted fenders and balloon tires, ended in 1942.
In spite of the Depression, there was a small but steady market for luxury motorcycles in the UK, which two leading manufacturers sought to satisfy. Having recently hired Edward Turner, Ariel’s Jack Sangster was rewarded with Turner’s first major design, the Square Four of 1930.
Four pistons drove two overhung crankshafts connected by gears, while a chain-driven overhead camshaft worked the valves. The result was an exceptionally compact unit that fitted easily into existing Ariel frame and cycle parts. The engine grew to 600cc for 1932, and underwent a complete redesign in 1938, producing the OHV 995cc model 4G.
Meanwhile in Plumstead, London, the enterprising Collier brothers of Matchless had also developed a square, four-cylinder OHC engine, but in this case with all the pistons driving a single crankshaft, and bevel gear camshaft drive. Released as the Silver Hawk in 1934, it survived in production for just three years. Post WWII and back at Ariel, the 4G gained a new frame with plunger rear suspension, then an alloy cylinder head and four exhaust headers for 1953. It continued with little change until expiring in 1959.
So were four-cylinder motorcycles worth the extra cost and complexity? Though smooth and relatively powerful, all of those described here suffered the same problems when their full power was used: overheating. It was Honda’s innovation of sitting all four cylinders out in the breeze that resolved the issue—and then liquid cooling, of course.
Ariel Square Four owners in particular suffered repeated digs about rear cylinders overheating, leading to the witty riposte: “When they do that, we take them off and put them on the front …”
– Robert Smith, July 2012 (issue #283)