Name Games: 1967 Norton/Matchless N15CS

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Stanley Krohn's 1967 Norton N15CS.
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The frame for the N15CS/G15CS came from Matchless and the engine was the 745cc parallel twin as used in the Norton Atlas, but with an AMC primary chaincase.
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Stanley Krohn's 1967 Norton N15CS.
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The frame for the N15CS/G15CS came from Matchless and the engine was the 745cc parallel twin as used in the Norton Atlas, but with an AMC primary chaincase.
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Something of a factory bitsa, the bodywork was sourced from the Matchless G12CS.
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Stanley Krohn's 1967 Norton N15CS.
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Stanley Krohn's 1967 Norton N15CS.
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Dual Amal Concentrics fuel this Norton N15CS, although it's fitted with the earlier magneto engine.
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A classic British face if ever there was one. The relatively narrow Norton Atlas engine is almost invisible in a head-on view, underscoring the slimness of Sixties British bikes.
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Stanley Krohn's 1967 Norton N15CS.
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Restorer Mark Zenor riding owner Stanley Krohn's 1967 Norton N15CS. The "CS" designation originated with Matchless, standing for "Competition/Spring frame."
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Stanley Krohn's 1967 Noorton N15CS.

1967 Norton/Matchless N15CS
Engine: Norton Atlas 745cc air-cooled OHV parallel twin, 73mm x 89mm bore and stroke, 7.5:1 compression ratio, 55hp @ 6,800rpm
Top speed: 100mph (est.)
Carburetion: Two Amal 389 Monobloc or 30mm Amal 930 Concentric (late models)
Transmission: 4-speed, chain final drive
Electrics: 12v, Lucas K2F magneto or coil and breaker points ignition (late models)
Frame/wheelbase: Matchless mild steel dual downtube double cradle frame/57in (1,448mm) (est.)
Suspension: Norton Roadholder telescopic forks front, dual shocks rear
Brakes: 8in (203mm) SLS drum front, 7in (178mm) SLS drum rear
Tires: 3.25 x 19in front, 4.25 x 18in rear
Weight (dry): 407lb (185kg)
Fuel capacity/MPG: 2.5gal (9.45ltr)/40mpg (est.)
Price then/now: NA/$6,000-$12,000

Putting one maker’s engine in another manufacturer’s frame became popular in Britain in the Sixties. First choice was usually the very tunable Triumph 500cc or 650cc twin in a Norton Featherbed frame. The result was called a Triton, a blend recognized as almost a model unto itself.

So what do you call a Matchless motorcycle with a Norton engine? A Matchton? A Nortless? Well, according to Associated Motorcycles, the owner of both brands, it was either or both a Matchless and a Norton, depending on which badge you preferred. Confused? You have a right to be, and there is an explanation — but first, some background.

Consolidation in the British motorcycle industry after World War II saw many brands absorbed into larger companies. When BSA bought Triumph in 1951, it became the biggest motorcycle manufacturer in the world at that time, also owning the Ariel, Sunbeam and New Hudson brands. Associated Motorcycles, the Matchless owners, had absorbed AJS in the 1930s, adding Francis-Barnett (1947), James (1951) and Norton (1952).

But by 1962, AMC was drowning in red ink, hit hard by the boom in imported scooters. To cut costs, they decided to close the crumbling and inefficient Norton plant in Birmingham and consolidate production at their Plumstead, London, factory.

Whether what happened next was planned or happenstance is moot, but it solved a number of issues for the company.

Finding a solution

Feeling the ever-present pressure for “more cubes” from its U.S. distributor, in 1962 AMC had launched a 750cc version of its own parallel twin as the Matchless model G15 (also known as the G15/45). In an attempt to mitigate mechanical issues (mostly crankshaft related), the 750 engine was detuned, yet it still proved unreliable, and the G15 was dropped in 1963.

And while the 750cc Norton Atlas had been selling well in the U.S., AMC realized it was missing out on a growing market for scrambler-oriented bikes because the featherbed frame used in the Atlas proved too fragile for off-highway use. Triumph and BSA had developed off-highway versions of their street bikes for desert racing that were both strong and handled well, the Triumph T120C and the BSA Wasp/Hornet.

But there was a solution. AMC had demonstrated that it had a strong enough frame for offroad use in the 650cc G12CS (CS for Competition/Spring frame) of the early Sixties, unfortunately abandoned because of engine reliability issues. And with Norton production now in-house in Plumstead, AMC had direct access to the reliable and reasonably powerful Atlas engine — even though it had been detuned with a 7.5:1 compression because of excessive vibration.

For 1964, the G15 was relaunched as the Mk2 and fitted with the 745cc Norton Atlas engine, Norton Roadholder fork, and Norton brakes — the first AMC-Norton hybrid. The sportier, café-style G15CSR (R for road) soon arrived with swept-back headers, rear-set footpegs and lower handlebars. It was mainly intended for the home market, though some did make it across the pond.

Alongside the G15 and G15CSR were AJS branded variants, identical but for the badge and paint: the Model 33 and 33CSR were usually finished in polychromatic blue.

Based on the 650cc G12CS, the G15CS Atlas Scrambler, with its AMC frame and Norton Atlas engine, was built specifically for export. For the G15CS, the dual cradle frame and swingarm were modified to accept a 2-inch-over Norton Roadholder fork (fitted with internals from AMC’s own Teledraulic unit) with steel tubes covering external springs, and a Norton rear wheel.

The Atlas engine was machined to accept the AMC alloy primary chaincase with drive to the AMC/Norton 4-speed gearbox. Gas and oil tanks and the battery box all came from the G12CS. The resulting bike was sold with a Norton badge as the G15CS/N Atlas Scrambler, and with the Matchless logo as the G15CS/M Matchless 750 Sports Scrambler. Both were finished in Cardinal Red.

They proved very competitive in desert racing, with Californian Mike Patrick winning the Cross-Country National Championship outright on an Atlas Scrambler in 1964, interrupting Triumph’s domination of the Open class.

For 1965, the G15CS was relaunched with a Norton logo as the N15CS, and with the new winged Matchless tank badge as the G15CS. Changes included a revised fork (now with Norton internals), and with gaiters rather than steel tube covers.

Production continued sporadically with numerous “serial” changes into 1967, by which time the N15CS was fitted with coil ignition replacing the magneto, Amal Concentric carburetors replacing the Monoblocs, and a new high-flow “six-start” oil pump. A slimmer seat and restyled fenders were fitted, and both the Norton and Matchless variants were finished in Cardinal Red.

When AMC ran out of money in 1966 and went bust, its assets were purchased from the receiver by Manganese-Bronze Holdings, and the company was re-formed as Norton-Villiers in early 1967.

New owner Dennis Poore had ambitious plans for the company, which included a new Norton to replace the Atlas — the forthcoming Commando. But another opportunity was about to present itself from the U.S.

California connection

The story goes that Joe Berliner of U.S. distributors Berliner Corp. saw an opportunity to create the ultimate British twin desert sled. AMC’s best offroad frame was the light-but-strong Reynolds 531 chromemoly dual downtube item used in the G85CS, the last of the Matchless line of offroad singles. But the 500cc single was down on power compared with the competition, and Berliner proposed an Atlas-powered version. However, AMC told Berliner they would be unable to fit the Atlas engine in the G85 chassis. Whether this was a technical or commercial decision is unclear.

California dealer Bob Blair of ZDS Motors in Glendale and his mechanic Steve Zabaro decided they would try. Blair had a G85CS with a crashed front end, which he fitted with a new fork and an Akront alloy rim laced to a Matchless hub. A new N15CS provided the donor engine. With suitable modifications and with Duralumin engine plates cut to suit, the Atlas engine was a snug fit in the G85 chassis, and became the prototype for the Norton P11 (Motorcycle Classics, September/October 2010).

Berliner sent the complete machine, together with Bob Blair, to the Plumstead factory to debrief what was required, and the first production P11 was built in March 1967. The basic concept, with numerous changes to components, remained in production for the following two years, through the P11A and street-legal P11 Ranger versions. The hybrid line was finally dropped in 1969 so the factory could concentrate on the Commando.

Stanley Krohn’s 1967 Norton N15CS

The N15CS was more mix ‘n match than just a Matchless with a Norton engine, like the P11. The N15CS featured here has an appropriate history.

It was originally sold by Pat’s Top Hat Cycle in Burien, Washington. “Pat” Patereau was the Norton and Ducati dealer for the area, and his son Jim went on to be an accomplished local competitor. Stanley Krohn bought the N15CS as a used bike from Pat’s in the late 1960s.

“Somewhere along the line it got kind of choppered out,” says Mark Zenor of Zenor’s Norton Service in Graham, Washington, who carried out the restoration. As Mark received it, it had the wrong rear fender and taillight. At the front was a different headlight, the forks had been modified 6 inches over, and it was topped off with “chopper bars that were the chrome twisted squares,” Zenor says.

Krohn had taken the Norton to a cycle shop that was going to rebuild the cylinder head, but the engine had never been reassembled, and the dismantled motorcycle sat in a shed for 18 years. “We got it out of that shed four years ago,” Zenor says “I finally got it done this fall.”

Zenor could tell there had been some head work, but “it sat out in the open uncovered for that whole time, so it all had to come back apart.” The cylinder head responded to the valves being re-lapped. Though the cylinder block was reusable, showing scuff marks and some minor scoring, Zenor replaced it after discovering a broken fin. Surprisingly, the bottom end was in good shape. “They’re pretty hard to beat up,” Zenor says, adding, “The gearbox wasn’t too terrible. A couple of gears had that usual spalling and pitting, which we took care of. The rest of it was really finding the little bits, like the proper fenders, mounts and stays.”

The seat proved especially problematic: “I don’t think that seat’s quite proper,” Zenor notes. “It’s in that in-between year.” N15s are usually shown with a seat without the all-round seam on Krohn’s bike. “I think it should have come with a little bit longer, skinnier, more rounded-looking seat, like you’d see on a Fastback, but I could never find one,” Zenor adds.

Zenor’s biggest challenge was “figuring out all the right nuts and bolts.” It seems AMC never published a separate illustrated parts book for the N15CS, just a supplemental listing. That made finding the right parts even more difficult. “Everything’s by number and period nomenclature. I’m doubly handicapped here. American English!” Zenor says. “It took me awhile to figure out ‘pins’ were ‘bolts.’ I worked with Mike Partridge at Walridge Motors. He’s got a bit of a sweet spot for these hybrids. He keeps a good stock. We swapped some stuff back and forth, and I ended up getting just about everything down to most of the fasteners.”

Zenor had the frame powder coated by American Powder Coating in Auburn, Washington (253-833-7870), to an “80 percent shine.” The sandblasting was done by Performance Coatings, and the painting was done by Moslander’s Rod and Custom in Monroe, Washington.

Putting it together revealed some interesting assembly protocol. “The centerstand and the bash plate. There’s nothing that tells you to put them on first. They should really go in place before you load the engine and gearbox in there. I’ve got them on, but now that I’ve experienced it, doing it again I’d put it together differently,” Zenor says.

Part of the problem is that the Norton engine is a pretty tight fit in the Matchless chassis, which makes adjusting the magneto almost impossible. “It becomes really apparent when you put it side-by-side with an Atlas, and you can see how that gearbox and engine was really spread out for the frame. It’s just leaps and bounds easier [the Atlas] to work on.”

The N15CS is a perfect example of how adversity sometimes creates opportunity. If AMC hadn’t decided to close Norton’s Bracebridge Street, Birmingham, factory and consolidate production of Matchless and Norton motorcycles in Plumstead, it’s quite possible no one would have thought of putting a Norton engine in a Matchless frame.

There’s no question that the success of the N15CS in the U.S. kept AMC/Norton-Villiers afloat until the Commando came along in 1968, adding another 10 years to the life of the aging Atlas engine. But that’s a whole other story…

Meanwhile, if you’d like to see Stanley’s N15CS in the flesh, it will be featured at the International Norton Owners Association Tall Timber Rally in Elma, Washington, from July 16-19, 2018. MC

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