Motorcycle Classics

Build a Vincent Rapide A Twin

Want a Vincent Rapide A twin? You could try building one … That’s what Vancouver resident Dan Smith did — though he also revised some features to suit his own preference and to take advantage of modern methods and materials. Helping Watson with the restoration of his Rapide gave Smith first-hand access to the A twin’s internals. Smith designed his crankshaft with two throws (spaced at 47 degrees) instead of one, to mimic the even firing of a parallel twin, but also to take advantage of improved primary balance forces. Custom engine cases were cast locally after several trips to the foundry to optimize the patterns, and then machined in Smith’s own basement shop. Smith’s iron-lined alloy cylinders and light alloy cylinder heads use a “bathtub” combustion chamber instead of Vincent’s hemi. “It used my equipment to the maximum,” Smith says, “especially machining the cases.”

Camshafts are to “MkII” Lightning spec. Smith cast his own carburetor bodies, then used internals from Amal 289s. Drive to the Burman gearbox is via a Yamaha clutch. Smith made his own frame to Vincent pattern but with larger diameter tubing where appropriate. He also re-tubed a set of Brampton forks and made his own aluminum brake drums with shrunk-in iron liners. The gas tank is a modified post-WWII Vincent item, and oil resides in a side-mounted oil tank made to mimic the A Twin’s toolbox.

The result is a heady mix of modern technology, traditional styling and the kind of upgrades that Vincent might well have made. Much, much more than a slavish copy, Smith’s Vincent Rapide A twin is an inventive and respectful homage to the genius of Philip Irving.

Read more about Watson’s Vincent Rapide A twin in Better Than One: The Legendary Vincent Series A Rapide.

  • Published on Jul 27, 2012
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