After not nearly enough testing, Norton releases the "Combat" engine. With a twin roller bearing crank, 10:1 compression and able to develope 65 bhp at 6,500 rpm. Reliability immediately suffered, with frequent and early crank-shaft main-bearing failures, sometimes leading to broken crankshafts. The earlier Cammando 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 was particularly obvious when measured against the reliability of the contemporary Japanese engines .
With the new engine the Commando was offered in several different styles: the standard street model, a pseudo-scrambler with upswept pipes and the Interstate, packaged as a long-distance tourer, which unfortunately became
short distance very quickly if used to the full on German Autobahns with the
atrocious Combat crankcase, that threw all its oil out of the breather at over
4.500rpm and stopped suddenly after all the oil had gone.
After 1973, with the
new crankcases, it actually was a very nice long-distance bike. Too late.
