Staying Single

Text: Robert Smith • Photography: Robert Smith

The design exemplifying the British motorcycle during its golden age in the 1920s and '30s was the overhead valve single of 350 or 500cc. Every major manufacturer made at least one, and it was usually their bestseller. Simplicity combined with an excellent power-to-weight ratio and (usually) nimble handling made such a machine an ideal mount for Britain's winding roads. BSA built their famous "sloper" and Empire Star models, Triumph its Tiger range, Velocette the sporty KSS. Sunbeam, Rudge, and Royal Enfield all had numerous big singles in the ranges. But perhaps the best of the bunch was Norton's 500cc ES2. It outlived all but the Velocette, which struggled on in limited production until 1971.

For the longest time, Norton only made singles. From 1910 until the Model 7 parallel twin arrived in 1949, the company listed just three engine sizes - 350cc, 500cc and 650cc - and all singles. The 500cc version, available as side valve, overhead valve or overhead cam, was the most popular. The 650cc "Big Four" came with side valves only and was intended for sidecar use.

When Ian Bardsley's 500cc Norton ES2 was dispatched from the famous Bracebridge Street factory in Birmingham, England, in 1957, the model had been listed in the brochure for almost 30 years. And while the 500cc long-stroke single was by then considered a real plodder, at its launch in 1928 it was one of Norton's sportier models.

In 1927, Alec Bennett won the Senior (500cc) Isle of Man TT on a new Norton with a Walter Moore-designed overhead camshaft engine. The next year, the "cammy" CS1 appeared in the catalogue for sale to the public together with a new street bike using many of the same components, but fitted with a new OHV engine. The ES2 sold alongside Norton's standard OHV 500, the Model 18, and the side-valve Model 16H. Interestingly, all four 500cc bikes shared the same internal dimensions of 79mm x 100mm bore and stroke, a characteristic that stayed with the ES2 until it was discontinued in 1963.

Detail changes followed the ES2 through the 1930s until it was dropped in 1939 so that Norton could concentrate on military production of the 16H, and although the Model 18 reappeared in 1946, it retained its pre-war girder forks and rigid frame. So when the ES2 returned in 1947 with plunger rear suspension and "Roadholder" telescopic forks, it was Norton's most prestigious model (after the expensive, limited production "cammy" International model). Through the fifties, improvements to the ES2 brought swinging arm rear suspension, an alloy cylinder head, and finally, in 1959, the coveted "featherbed" frame. Meanwhile, Norton had been absorbed by Associated Motorcycles, so the ES2 also gained AMC's group gearbox.

The times conspired against the ES2, though, and big single-cylinder bikes in general. Twins like Norton's own Dominator now set the performance standard, and singles were mostly promoted as sidecar "tugs." And when small cars like the Mini displaced sidecars, the end was near. Production continued until 1963 when the last ES2 left the AMC factory in Plumstead, London. AMC had closed the Bracebridge Street works in 1960. The ES2 name resurfaced in 1965 for one season only, attached to a Norton-badged AMC 500 single.

Ian's bike
Ian Bardsley located his 1957 ES2 ten years ago through the Internet. It had been imported from India to Calgary, Canada, where its owner claimed it was still in regular use.

"It looked better than it actually was," says Ian. "It was complete, but just looked shabby. I even got it to run once, but trying to restart it [the kickstarter] bit me severely in the foot!"

"My idea was to ride it, and fix the mechanical bits as necessary rather than do a complete restoration. "That ambition ended when Ian started tinkering with the front wheel. That led to the forks, which led to...

"Two days later, I had the whole bike apart. It took me seven years to put it back together." The engine contained a number of horrors. For a start, the cylinder bore was under-size. "The barrel had been re-sleeved," says Ian, "and I suspect the piston had been turned down to fit." The timing case was cracked and needed welding; the cams were worn out and the timing marks incorrect. Parts were missing from the lubrication system. The flywheels had been improperly assembled, causing the main bearings to work their way out of the engine cases. Ian had the crankshaft rebuilt and properly aligned with new main and big end bearings. Cams were reground.

"The only part of the magneto that was salvageable was the rotor," says Ian. It needed a new housing, bearings, points, capacitor and end cap! Then came the clutch: "To say it was hanging by a thread would be an understatement." The cush rubbers were completely gone from the clutch hub, as were most of the friction inserts. Ian replaced the complete unit with a clutch from a Dominator.

"What's remarkable," Ian says, "is just how worn out everything was."

One strange anomaly was that the speedometer wasn't working when Ian got the bike, and the odometer read 0 miles. Ian removed the unit from its housing, cleaned it and replaced it, and it's worked fine ever since.

The completed restoration is a credit to Ian's patience and his engineering skill, to the point where the notoriously incontinent Norton "oil bath" chaincase is leak-free. Correct period decals, tank badges and knee grips complement the polished alloy and chrome, which highlight the traditional Norton gloss black and silver paint scheme. But what's it like to ride?

"My expectations were that it would be a modest back-lane plodder," says Ian, "but its performance surprised me. It will keep up with modern traffic, admittedly in the slow lane, and it will cruise all day at 55mph. The handling is surprisingly good, very predictable. I'm sure the featherbed is better, but..."

"Power delivery is lumpy as you'd expect from a single, but the vibration isn't bad - not as severe as a Triumph 650, for example. At a reasonable cruise speed, it's quite comfortable."

"My goal was to have an interesting rider, and it's certainly fulfilled that. It's not an everyday machine, perhaps, but it's a nice weekend bike."