1951 Triumph 650cc 6T Thunderbird Bobber

Always a step ahead of their rivals, Triumph followed up the trend-setting Speed Twin 500 of pre-war days by being first in the field with a 650cc parallel twin. Announced in September 1949, the 650 Thunderbird was Triumph’s response to demands for more power emanating from American racers and British sidecarists alike. A spectacular launch stunt saw three Thunderbirds lap the banked Montlhéry circuit in France at over 90mph for 500 miles, after which they each achieved a flying lap of 100mph-plus and were ridden back to the Meriden factory, a quite outstanding achievement.

Post-World War II, many returning servicemen, looking for thrills, turned to motorcycles for their fun. And modifying them became a way to express their individuality. Café Racers in London competed against each other on the road and with Italian scooters in the style forum, while the Americans were removing front fenders, chopping the bike around and shortening rear fenders, or “bobbing” them, for the Bobber-look.

The motorbike offered

The 1951 Triumph 6T Thinderbird Bobber on offer here comes to us from a Southern California collector/restorer/racer/land speed record holder in various classes and all-round enthusiast. The bike was fully restored from the ground up in his extensive and clinical workshop. Starting at its heart, the engine features new main bearings, rod bearings, wrist pin bushings, rebore with 0.020 pistons, new rings, larger intake and exhaust valves, valve guides and springs. The head was milled, tappets resurfaced, and 3134 cams and Morgo oil pump installed. The crankshaft was fully balanced. Carbs are new Amal 389 Monoblocs.

The clutch was upgraded installed with new primary chain and cushdrive rubbers. The gearbox was overhauled with new bearings, seals, and cam plate.

The bike was converted to 12 Volt and has a rebuilt magneto.

This is all housed in a restored, matching numbers frame with rebuilt forks with new bushings, seals and springs. New wheel rims with stainless spokes are shod with new tires. A new chain and brake shoes installed.

The Mercedes dark metallic blue paint on the tank is exquisite, professionally applied. Brightwork is fresh and a new seat provides a pleasant place to sit.

The bike starts readily, idles smoothly and rides exceptionally well. With only a few shakedown miles since such a comprehensive restoration, the bike only needs a new, enthusiastic bar-hopping owner.