The 750 Norton Atlas was noted for its vibration. Rather than change engines Norton decided to change the frame, and the isolastic-framed Norton Commando 750 was the result.
In 1969, the Commando was introduced. Its styling, innovative isolastic frame and powerful engine made it an appealing package. The Commando easily outperformed contemporary Triumph and BSA twins and was the most powerful and best-handling British motorcycle of its day. The isolastic frame made it much smoother than the Atlas. It used rubber bushes to isolate the engine and swinging arm from the frame, forks, and rider. However, as the steel-shims incorporated in the Isolastic bearings wore, often from rusting, the bike became prone to fishtailing in high-speed turns.[clarification needed]
The "Combat" engine was released in January 1972, with a twin roller bearing crank, 10:1 compression and developing 65 bhp (48 kW) at 6,500 rpm. Reliability immediately suffered, with frequent and early crank-shaft main-bearing failures, sometimes leading to broken crankshafts. Older engines had used one ball-bearing main bearing and one roller bearing main bearing but the Combat engine featured two roller bearings in a mistaken belief this would strengthen the bottom-end to cope with the higher power-output. Instead the resultant crank-bending caused the rollers to "dig-in" to the races, causing rapid failure. This fragility did not show up well,[clarification needed] especially when compared with the reliability of contemporary Japanese machines.[12]
The Commando was offered in several different styles: the standard street model, a pseudo-scrambler with upswept pipes and the Interstate, packaged as a tourer. Electric start was introduced in 1974. Sales were respectable but the company declined financially and became insolvent in 1975.[5] In 1976 a Norton with a US-flag theme on the tank could be purchased for US$1,976.
