Hi,
Picked up a book in a Charity shop, called Classic British Motorcycles 1950 to 1975, by Steve Wilson, ISBN: 0-86288-471-3, its an American publication I think, tires, color e.t.c. Factories are dealt with by the most successful models to hit USA, improvements & set backs, cost cutting, Designer & Factory input, recommendations By Agents, Importers & Tuners, OK, the models are generally more exotic, (Blingy), than Home market stuff, it deals with responses to racing needs, collapse of Home Market in 1959. All in all a a very refreshing read, more useful than many other publications I have seen. Not quite the same old stuff regurgitated!
Oh! For those running or buying stuff from abroad, where it dusty & dry catch David Vizard on You Tube talking about engine filtration & K&N's.
Cheers
John