Norton Jubilee Explained

Norton Jubilee
Manufacturer:Norton Motorcycles
Production:1958-1966
Engine:249cc air cooled twin
Power:16bhp @7,750rpm
Transmission:Four-speed, chain final drive
Wheelbase:53.5inches
Wet Weight:330lb

The Jubilee is a Norton motorcycle made from 1958 to 1966.[1] Named to commemorate Norton's Diamond Jubilee, the 249 cc Jubilee was a break with Norton tradition designed in response to UK legislation[2] introduced in 1960 limiting learner riders to motorcycles of under 250 cc.[3] It had the smallest engine ever made by Norton, and was the first Norton with a unit construction engine and gearbox.

Development

Launched in 1958 the Norton Jubilee was named in celebration of Norton Motorcycles' Diamond Jubilee of 60 years of motorcycle manufacture. The engine was a new design by Bert Hopwood with main and big-end bearings identical to those used on Hopwood's Norton Dominator engine[4] ten years before. Having the smallest Norton engine, the Jubilee was also the first Norton with a unit construction engine and gearbox. The engine dimensions of 60mm x 44mm gave it a short stroke and produced only 16bhp at 7,750 rpm. It required high revs to reach usable speeds, and had a maximum speed of 75mph.[5]

Designed around an unusual crank in which the central flywheel had a narrow section but large diameter, the new engine gained a reputation for oil leaks and unreliability. After Hopwood changed the crankshaft material from cast to nodular iron and improved the gearbox layshaft bush, the Jubilee proved more reliable and sales slowly increased.

The new engine was in an old frame and the gearbox from older motorcycles in the AMC Group's range. The front frame tube was a steel pressing and the lightweight forks, brakes and wheels were Francis-Barnett parts. The rear enclosure came from sister company Clarendon Pressings. The gearbox was the same as in the AMC 2 stroke Piatti engine and the AJS and Matchless lightweight motorcycles.[6]

Originally sold as a 'De Luxe' model with a fully enclosed rear end, the Standard model arrived in 1961, continuing in production until 1966. An estimated 5,000 Jubilees were built at Norton's Bracebridge Street works before production was transferred to the AMC Woolwich factory in 1963.

Notes and References

  1. Book: Reynolds, Jim. Best of British Bikes. Patrick Stephens Ltd. 1990. 978-1-85260-033-4. registration.
  2. Book: Westworth, Frank. The British Classic Bike Guide. Haynes Publishing. 978-1-85960-426-7. 1998.
  3. Web site: Chronology of Motorcycle Legislation in Britain. 2013-12-08. https://web.archive.org/web/20160304032610/http://www.network.mag-uk.org/january_00/chronology.html. 4 March 2016. dead.
  4. Web site: Norton Jubilee 250. 2009-03-26.
  5. Web site: Norton Jubilee 250cc . The National Motor Museum Trust . 14 January 2022.
  6. Web site: The Norton Lightweight Twins . Sochanik . Andy . Norton Owners Club . 1992 . 14 January 2022.