Classic Racer Nov/Dec `07 J.P.N. feature, mentions the short strokes as being good for "78 bhp @ 7,200rpm" & using "one - piece cranks - an effort to save smashing crankcases with the flexing of built -up cranks"
Mick Grant is quoted;
"They`d regularly bust crankcases, in fact one time I had a flywheel break up, which bust out one side of the cases & punctured the back tyre."
Frank Perris, team boss, reckoned that Norton were happy to freely provide production parts in quantity, so I `spose the feedback enabled the stronger set-up for the 850 Mk III Commando?