Norton Commando & Norton Manx

Norton is one of the oldest names in motorcycle manufacturing, having been founded in Birmingham, England in 1898.  It began building motorcycles in 1902, using numerous components acquired from a variety of suppliers.  They came out with their own engine, a 3.5 hp single some six years later.  Much of its sporadic prosperity came from military contracts, which corresponded with the timing of various armed conflicts.  The company experienced periodic financial difficulties over the years, and was re-structured, sold, and merged with other companies over time.

The Norton Commando was the successor to the Norton Atlas, a 750cc vertical twin.  While the Atlas employed the widely touted “featherbed frame, it suffered from vibration difficulties.  In 1968, the new Commando introduced what they called the “isolastic frame,” and incorporated a forward leaning 750cc engine configuration.  The new arrangement solved the vibration problem, and resulted in a bike which outperformed competing British twins of the day.

The famous Norton Manx was a single cylinder racing bike designed specifically for the Isle of Mann TT (Tourist Trophy) race.  This hazardous race, conducted on an island off the west coast of Great Britain, has been held annually for 125 years.  The Manx was produced in limited numbers in both 350cc and 500cc displacements.  It used a single cylinder with double overhead cams (DOHC).

The Manx used a standard DOHC valve set-up with conventional valve springs.  During the Manx’s final years, Norton experimented with a desmodromic cam layout, which uses cams to both open and close the valves without relying on valve springs.  Theoretically this increased the rev range due to the absence of “valve float.”  However, the valve clearance is highly critical and difficult to maintain as the engine heats up.  Norton was unable to get any better track performance with it than it could with the standard DOHC engine, and the desmodromic Manx never went into production.

The rights to the Norton trademark have changed hands multiple times over the years, and are now held by an Indian company with manufacturing facilities in the UK.