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AMA Vintage Days are on the way

Posted By John Phillips, Wednesday, May 25, 2016

AMA Vintage Days are fast approaching and Gary and I are feeling the pressure to complete rebuild projects begun last Fall, my '74 850 Norton Commando and his '54 Vincent Series D Rapide. The unanticipated surprises that arise in such frame-up restorations are stressing the schedule and unfortunately mean that riding my '84 R 100 (S) and Gary's '81 R 100 RS are a second priority for both of us until after AMA.

Meanwhile, it is interesting to contrast the similarities and differences in design approaches of 40- and 60-year-old vertical twin, V-twin and boxer twin airhead technologies. The Mk II Commando was the next to last model built by Norton Villiers before production ceased in '76. By then, Norton had addressed all of the major weaknesses from expanding a 1947 30 h.p. 500cc vertical twin to a 56 h.p. 828cc in 1973. The final Commandos were decent performing, fundamentally reliable motorcycles by 1973 standards, but had maxed out their design limits. Without further innovation and capital infusion, Norton's fate, and the fate of the British motorcycle industry generally, was sealed by a flood of rapidly advancing, better performing and less fiddly Japanese imports.

A close look at the Vincent reveals notable innovations and a high attention to quality in the era before computer aided engineering and manufacturing. Vincent kept refining its 1,000 cc V-twin motor from the 1930s until limited market demand and rising costs ended production in 1955. The Vincent motor was all aluminum alloy, a feature not adopted by Harley big twins until the Evo engine of 1981. Vincent introduced the motor as a stressed member of the frame, an innovation adopted by the Yamaha Virago of the '80s and of course, by Ducati. The Series D Rapide pioneered the use of a monoshock rear suspension, adopted by Harley for its Softtail, and today by virtually all modern sport bikes, including BMW.

An all-alloy engine that is a stressed member of the frame, mono-shock rear suspension and monoshock girder front end that is adjustable for side car use were hallmark innovations of the last Vincent series, the D Rapide of 1954. Due to gas quality in England at that time, the low compression 1,000 cc motor was rated at about 45 h.p.

The clock is ticking. Both bikes are going to Mid Ohio come Hell or high water. Gary and I will swap rides when they're done. I'm getting the better end of the deal. Can't wait to buckle on the Go-Pro to record for family posterity my first and maybe my one and only ride on a Vincent motorcycle.

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