Featured in the July 2019 Issue of Roadracing World:
The 1974 JPN (John Player Norton) factory racebikes
reflected internal politics and personalities more than race objective
development and engineering.
While not directly involved with the Norton race
shop, our band of factory development guys (I worked in the development
department at the time) could see that the 1974 racebike’s lap times were
slower than the lap times turned by the 1973 JPN monocoque (See Historic
Racebike Illustrations, Roadracing World, July 2013). While doing research for
this illustration some of the wrong turns became more obvious.
The 1973 bike was the brainchild of chief engineer
Peter Williams and a radical departure from conventional thinking. Williams, a
gifted engineer and rider, was soft-spoken and did not have a dominating
personality, which resulted in others (mainly, retired 125cc and 250cc GP racer
Frank Perris) having a major influence on the design of the 1974 racebike.
The monocoque was replaced with a lighter ‘space
frame’ chassis built of straight thin-wall steel tubes that still incorporated
the Isolastic™ mounts that isolated engine vibration from the rider and
chassis.
Although the 1973 geometry was retained, the engine
was positioned higher and the pannier gas tanks abandoned. This latter change required use of
an extra gas tank located behind and under the seat, possibly the worst
location for stable handling!
The seat and both tanks (front and rear) were
incorporated into a one-piece unit attached with quick-release fasteners and
rubber bands for easy pit access. A large, ribbed oil tank located in front of
the engine between the header pipes negated the need for a separate oil-cooler.
With minor modifications, forks, wheels and brakes were carried over from the
monocoque, as was the distinctive, aerodynamic fairing …
Historic Racebike Illustrations by Mick Ofield, in the July 2019 issue of Roadracing World
Newer is not always better in
the case of road racing motorcycles. Roadracing World looks at how the changes
to the 1974 John Player Norton factory racebikes were a step back from the
radical machines that challenged tradition a
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