Falloon’s Favourites: Norton 650 SS

For many enthusiasts, the Norton 650 SS remains the definitive sporting Norton twin. Combining the legendary Featherbed frame with a classic 650cc British parallel twin resulted in a masterpiece…

One of the most influential of all motorcycle frame designs was Rex McCandless’ “Featherbed” frame. This double cradle design comprised two complete tubular loops that crossed at the steering head. When it appeared in the works Manx Norton single cylinder racers during 1950 it immediately set a new standard for handling and road holding.

So comfortable was the ride that racer Harold Daniel dubbed it the “Featherbed”. With the Featherbed Manx, Norton went on to win several World Championships and TTs, and the Norton name became associated with excellent handling. Soon the Featherbed spawned copies and replicas by other manufacturers, even the Japanese, this lasting well into the 1970s. But Norton had it first.

The success of the racing Manx during 1951 saw customers clamouring for a production street twin with the new Featherbed frame. This appeared as the 500cc Model 88 Dominator de-luxe for the 1952 season. By 1956 the range was expanded to include the 600cc Model 99 and for 1961 there was a new 646cc version, listed as the Manxman, primarily for the US market. Then for 1962 Norton released their definitive 650 twin, the sporting 650 SS (super sports or sports special).

Powering the 650 SS was a parallel twin developed from Norton’s first Model 7. Designed by Bert Hopwood in 1948 to counter Triumph’s now decade old Speed Twin, the 500cc Model 7 was also a 360-degree twin with vertically split crankcases.

Unlike the Triumph, Norton’s twin had a single camshaft, positioned in front of the engine, but the two overhead valves per cylinder were still operated by pushrods and rockers. The Model 7 was a long stroke design and as it grew in capacity this characteristic remained. The new 650 retained the 68mm bore of the 597cc Dominator 99, but new crankcases and crankshaft saw the stroke increase from 82 to 89mm.

The crankshaft included a wider flywheel and larger, 44.5mm, diameter crankpins. The 650 SS also featured a downdraft cylinder head with larger inlet tracts, polished ports, and twin 27mm Amal Monobloc carburettors. Providing further performance over the standard 650 was a Manxman camshaft while a Lucas magneto rather than coil ignition provided the spark.

The electrical system was still a weak 6-volt and the AMC gearbox only four-speed. With an 8.9:1 compression ratio the 650 SS put out a claimed 49 horsepower at 6,800 rpm. This was enough for a maximum speed of nearly 190 km/h, if you could survive the rather excessive vibration.

The Featherbed frame used on the production models differed to the racing Manx versions in that it was constructed of mild steel tubing rather than the more exotic Reynolds chrome moly. During 1955 it adopted a welded rear subframe and a braced steering head, and from 1960 was narrowed at the top to allow for a slimmer tank and seat. This was known as the slimline (as opposed to the wideline).

Combined with a firmly damped Norton Roadholder fork and a pair of Girling shock absorbers, the handling for the day was exemplary. The 650 SS rolled on a pair of 19-inch wheels and stopped courtesy of a pair of full width drum brakes.

Compact, low, and functional, Norton finally hit the nail on the head with the 650 SS. Coinciding with the height of the rocker era, at around 180kg the 650 SS weighed little more than a 500 twin. Norton 650 SSs were extremely successful production racers, winning the Thruxton 500-mile production race from 1962 through until 1964. Future World Champion Phil Read teamed with Brian Setchell to win in 1962 and 1963, Setchell winning with Derek Woodman in 1964.

Over the years Norton company changed hands several times. They were absorbed by AMC in 1953 and became Norton-Villiers in 1966. The final gasp for Norton was the merging with Triumph before that also went into receivership in 1975. During this time the 650 twin was continually developed.

The 650 SS gained 12-volt electrics in 1964 and Amal Concentric carburettors in 1966, and in response to American requests the engine was enlarged for the 750cc Atlas that first appeared in 1964. Over the next two years interchanging of components saw Norton Atlas engines in Matchless frames and Matchless singles in Norton frames. None of this could stave off the inevitable collapse and eventually out of AMC’s ashes came the Norton Commando. But despite the Commando’s success, for many enthusiasts the 650 SS remains the definitive sporting Norton twin.

Ian Falloon

Australia’s go-to-guy for classic motorcycle wisdom. Ian has written nearly 45 books on motorcycles that each offer unparalleled insight on the historical and technical development of particular makes and models.