It was perhaps inevitable that Triumph would produce a true retro-bike; which manufacturer, after all, has a more fitting heritage on which to draw? The company first sounded out the market with the Thunderbird, which was really just the standard steel-frame modular triple in a zoot suit, but strong sales showed the potential.
Now along comes the Bonneville twin, bearing an illustrious name and simply oozing Britbike style.
The original Bonneville was a twin-carburettor version of the 649cc Tiger 110, running a high (by the standards of the day) 8.5:1 compression ratio and producing 34kW at 6200rpm. It got its name from the Bonneville salt flats in Utah where Johnny Allen was timed at an incredible 342km/h on a very special Triumph in 1956.
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The bike remained in production from 1959 to 1975 with gradual upgrades to 744cc and 39kW. Hinckley claims the new Bonnie is based on the 1969 version, reputedly the prettiest motorcycle yet built in Britain.
The bike bears an illustrious name and oozes style instead of oil. It’s built around a 790cc air-cooled vertical (and I do mean vertical!) twin with a sharply oversquare 86 x 68mm bore and stroke, fed by two Kei Him CV carbs. Although it looks like a pushrod motor, it has two overhead camshafts driven by a central chain and supposedly kicks out 45kW at 7400rpm.
Claimed torque is a more realistic 60Nm at 3500rpm.
In contrast to Nipponese parallel twins, the Bonneville is laid out with 360-degree firing order … both pistons rise and drop together and fire alternately rather than with the crankshaft throws at 180 degrees and the pistons in opposition. This gives the Britbike its characteristic easy idle and bottom-end grunt.
Transmission is by means of a conventional wet multiplate clutch and five-speed gearbox, remarkable only for its very slick shifts in both directions; almost undetectable clutchless upshifts are easy.
It’s built around a 790cc air-cooled vertical twin.
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