Norton Dominator 99
Norton Dominator 99 Background & History
The Norton Dominator 99 followed on the success of its older brother the Norton Dominator 88. They were essentially the same bike with one exception: displacement. The “Domi” 88 had 500cc and the Domi 99 was bored and stroked out to 600cc. The 88 made 31 hp and topped out at 90 mph, which gave them no hope of catching Triumph's 650 Thunderbird or BSA Golden Flash. In those days, “making the ton” (hitting 100 mph) was a really big deal and the few bikes that could do it attained sainthood in the minds of buyers.
This 1960 Norton Dominator 99 is on display at the Barber Motorsports Museum in Leeds, AL.
Norton Dominator 99 Engine Design
Norton had poached engine designer Bert Hopwood from Triumph to design their new vertical twin engine in the late 1940s. Hopwood had worked under legendary designers Val Page at Ariel, and Edward Turner at Triumph. He had assisted Turner in the design of the seminal Triumph Speed Twin. Where Triumph used gears to run its two cams, Hopwood positioned the single camshaft in the front of the engine, chain driven off the crankshaft. Spark was supplied by a Lucan magneto located behind the cylinders and driven by a chain. For lights, a Lucas dynamo was located in front of the cylinders and also chain driven. The crankshaft rode on two main bearings (no center main bearing) with the timing side on the right and the drive side on the left. The cylinder block and head were cast in iron, and the head featured cast-in rocker boxes rather than bolt-on boxes like the Triumph twin. However, Hopwood left Norton in the early 1950s and returned to BSA where he redesigned Val Page’s earlier BSA twin to make the BSA Golden Flash. In 1955 he returned to Norton just in time to oversee the expansion of the 500cc Model 7 twin into a 600cc beast. It now made 44 hp at 6,750 rpm, which allowed for higher gearing which in turn broke the 100 mph barrier with a 101 mph top speed! Amazing what 100cc of displacement will do.
This gorgeous 1959 Norton Dominator 99 was shown at the Clubmans All-British Motorcycle Show in San Jose CA in 2013.
Norton Dominator 99 Features
The Norton Dominator 99 stayed in production from 1956 through 1962 when it was supplanted by the Norton Dominator 650SS with, you guessed it, 650cc of displacement. But during its tour of duty the Domi 99 performed well on the street, on the track and in showrooms. It was very fast and handled better than any other motorcycle on the market, thanks to the much-vaunted Featherbed Frame. By the close of the 1950s, the entire Dominator line benefitted from a new cast alloy cylinder head, alternator-based electrical system (gone was the dynamo) and a points-and-coil ignition system (out with the magneto).
The 600cc Norton Dominator 99 was fed by a single Amal Monobloc carburetor. 1959 was the first year for the alloy cylinder head.
Norton Dominator 99 gets the Featherbed Frame
The Featherbed Frame was built out of two 20-foot lengths high-strength Reynolds steel tubing, each bent in one piece to form one side of the frame. This unbroken line started at the steering head, looped down around the engine then up towards the seat while gently curving forward to form the backbone, all with smooth, graceful bends for strength. The entire frame was welded together, an uncommon practice at the time. Most frames were held together with brazed-on lugs, which were heavy cast pieces that held the ends of the tubes together. They were heavy and not very rigid. The Featherbed was the opposite, it was light, incredibly strong and totally rigid. The McCandless Brothers (who invented the frame) built in an ideal frame geometry for high speed stability and handling and it worked! Any bike with a Featherbed Frame could out-handle anything else on the market. It was introduced in 1949 on the Norton Manx road racing machine but it took until 1952 for it to trickle down to the street bikes. The 1952 Norton Dominator 88 was the first, and every twin that Norton made from then on would use this frame, until the arrival of the Norton Commando in 1968. One frame from 1949 through 1968? 20 years is an eternity in the motorcycle business. It’s a testament to just how good the Featherbed Frame was.
That curved section of tubing on right that wraps around the side cover, and disappears under the seat is the most visible section of one solid, unbroken, 20-foot piece of high-strength steel that starts and finishes at the steering head, after wrapping the engine. This curve is the quickest way to spot a Featherbed Frame.
Room to Grow
As for Norton’s trusty twin-cylinder engine, it started out life at 500cc in 1949. Throughout the 1950s, it grew to 600cc, then 650cc, and in 1962 it grew to 750cc where it would stay through the 1960s. But in 1973, they did it again and bored it out to 850cc (828cc, actually). Think about that: the same engine stretched from 500cc to 850 over a period of 25 years. Nothing lasts that long today.
This 1962 Norton Dominator 99 represents the final year of production for this model. It was replaced by the Norton Dominator 650SS.
Norton Dominator 99 Books
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