The CB450 had a distinctive chrome-sided fuel tank, and shared Honda's 'family' styling found elsewhere on the S90 and CD175. Early models were known as the 'Black Bomber', or 'Dragon', but in Canada the K1 model was marketed as the 'Hellcat'. The Mk.I 'Black Bomber' was first shown in UK during the Diamond Jubilee Brighton Speed Trials of September 1965, traditionally held along the seafront. The bike was newly imported and its engine was not run-in, yet in a semi-competition demonstration sprint, the CB450, ridden by Allan Robinson, MBE, achieved a standing-start kilometre time of 30.1 seconds and a terminal speed of. Afterwards, the CB450 was exhibited at a motorcycle show at the Brighton Metropole Hotel exhibition centre. In December 1965, the UKmagazineMotor Cycle reported that UK sales were planned from February 1966, its price of £360 being the equivalent cost to a conventional British 650cc pushrod parallel-twin. In a further publicity event, Honda entered Mike Hailwood as one of the riders in the Motor Cycle500 mile production race at Brands Hatch during July 1966. However, Hailwood was able to complete only some demonstration laps on the CB450 before racing began, as it was barred from competing in the 500cc category, because the FIM had deemed that it "could not be classified as a production machine as it had two overhead camshafts"! Although the CB450's sales never matched Honda's expectations, the bike had excellent engineering for the time, including reliable electrical components, an electric starter, and a horizontally split crankcase, all features distinct from current British twins. A radical feature was the valve springing: instead of the conventional coil springs, it used 'torsion bars' – rods of steel that twisted to provide the spring effect. The four-speed K0 model was updated in the K1 model produced from 1968 with a redesigned fuel tank, rubber-gaitered front forks instead of sliding metal shrouds, a five-speed gearbox and twin speedometer and rev-counterinstruments mounted above the headlamp. Later developments progressed through a series of 'K' models with various improvements and styling changes including a single front disc brake, continuing to K7 versions in some markets, until the introduction of the CB500T in 1975. The basic engine was modified and installed in the Honda N360 car and the exported N600, the precursor to the Honda Civic.
