Norton Dominator Model 7.
The Dominator Model 7 had a 497cc iron head engine with a plunger frame and a single twin-spark magneto. Norton stuck with a 360-degree crankshaft layout with a single camshaft at the front of the engine driven by gears and chain. Having the rockers integral with the head meant there were less gasket faces to leak - and less valve noise. The bore and stroke dimensions also made for a longer stroke resulting in more torque low down. In 1953 the Model 7 was upgraded with a swinging arm frame, 19in front wheel and a 'pear shaped' silencer as Model 88. The Model 7 continued in production through to 1955 and was often used with a side car as they could not be fitted to the Featherbed frame Dominators.
Norton Dominator Model 88.
The Featherbed frame, designed for Norton by the McCandless brothers, were made by the Reynolds company as the outdated Norton works didn't have the necessary modern welding capacity for its manufacture. It was this new Featherbed frame that led to the Model 88 Dominator (also called the 'De Luxe') used the same 497cc engine and was developed in 1951 to be capable of 90mph and had the best brakes of any British motorcycle of the time. Originally developed for export it was sold on the home market from 1953. The 88 suffered from oil leaks from the primary chaincase but it was the outdated and inefficient Norton works that resulted in quality control issues for the 200 Model 88's produced each week.
Norton Dominator Model 99.
The 596cc Model 99 Dominator was introduced in 1956. As well as increased engine capacity, the 99 had a power output increased to 31bhp, due to a higher compression ratio.
Norton Dominator Model 77.
The 596cc Model 77 Dominator was introduced in 1956. Essentially a swinging arm, single downtube ES2 chassis with a 600cc Dominator 99 engine, it was in production at the same time as the Dommi 99 as a sidecar motorcycle but was dropped from production in 1957 when sidecar Featherbeds were introduced.
Norton Dominator 650SS.
In 1960 the featherbed frame was altered so that the top rails were closer together to create what became known as the 'slimline featherbed'. A 650cc twin carburettor engine was installed to create the Norton Dominator 650SS which was capable of 110 mph. The 'SS' stood for Super Sports and the 600cc models were discontinued to concentrate on production of the 650SS, which quickly earned a reputation as the best of the Dommies.
Source: Graces Guide