Amid much upheaval in management back in England and commotion among its American dealership body, Triumph nevertheless sent another great T120R Bonneville 650 to the United States for 1966. This year, revisions to the engine encompassed a new lightweight crankshaft and flywheel, re-profiled camshaft, and pistons that raised the compression ratio to 9:1. Larger carburetors would be introduced during the year as well. The Bonnie could achieve high speeds, but straight-line stability was an issue. Doug Hele, remembered as the “thoughtful genius” behind engineering development, changed the steering head angle from 25 to 28 degrees of rake to cure the problem.

Other new components included the 12-volt electrical system and larger and more rigid front brake. While oil capacity was increased to 3 quarts, the “slim-line” gas tank, white with Grenadier red trim, held only 2.5 gallons of fuel. And utilitarian considerations took another blow when the tank’s traditional parcel rack disappeared. Rather than the miniature grille that had served as the bike’s tank badge, there was now sleek eyebrow of chrome on the 1966 Triumph T120R Bonneville. Gray handgrips were adopted this year as well, and both stainless steel fenders and a handsome aluminum tail lamp housing were adopted.

In addition to the T120R Bonneville street bike, T120C was again offered for street-scrambler riders and the hot-looking, high-compression T120TT already had Evel Knievel thinking about jumping the Caesar’s Palace fountain. Triumph’s victories in the Daytona 200, Springfield Mile, and in various enduros reasserted the brand’s performance leadership. All Bonnevilles carried plenty of swagger.