The Norton Combat occupies a weird niche in the collectible motorcycle market. It is essentially a 1972 Roadster with a ‘specially tuned’ motor that broke with ugly frequency. They are valued at least as highly as the regular Commando and possibly more if the proper work has been done to the motor.
The Combat engine had higher compression due to a shaved head, a long duration high lift cam that was really good at the high end of the power band and added about 2000 useable revs to the motor. The set up wasn’t particularly good on the low and mid range so Norton changed the primary and actually geared the bike down. Which led to serious over revving and the pistons to separate from their crowns. Bad.
If that weren’t enough for one motor, the cam chains were near impossible to adjust which was often skipped at service. Led to really bad ignition timing (with a bad auto advance system) that led to hard starting, poor running and early exit for the bottom end of the motor which was weak from the factory.
The 1972 Norton Commando Combat used a 745CC air cooled four stroke overhead valve twin cylinder motor that made 65 HP. Overall gearing was lower on the Combat than the regular Commando which kept the top speed at 108 MPH. The legendary frame, Roadholder forks, swingarm/shock rear and isolastic motor mounts made it smooth and gave the bike exceptional handling.