1966 Norton Atlas 750
With the developed of the parallel twin in the mid 1930’s, most manufactures built their own twin to compete in the home and world market. For Norton their twin appears to have gone though a lot of boring and stroking, and the end result was the 750cc engine that powers this 1966 Norton Atlas 750.
Beginning as a 500cc twin for their Dominator line of the mid 1950’s the Norton Twin was first stroked to 600cc. It was later bored to 650cc, and finally stroked again to 750cc for the power/displacement hungry US market. All the while, vibration was a problem that had to be addressed. Lowering the compression ratio helped a little, but a stronger engine case, a stronger crank and better oiling were all needed to keep the engine together against the pounding. Addressing the vibration later lead to the Isolastic Suspension found on the Commando.
From the seller
This bike is in mint condition and has been stored in a heated garage. I bought the bike in the late winter to ride with my other buddies who own vintage Brit bikes. My wife is pregnant so most of my riding days will soon be behind me. The numbers are matching, I have the original bars and seat. The bikes comes with Bates cocktail shakers, but I put the original mufflers back on. Tires are minty… All the electrical is sound. Everything works including the gauges, lights and horn.
The 73cm bore and 89cm stroke pounded out between 55bhp and 58bhp. First developed in 1962 the lower horse power rating was because of a lower 7.6:1 compression ratio and a single Amal carburetor. This rating went up when the compression ratio went to 8.9:1 and a second carburetor was added in 1966. Once again the styling for the US market bikes would be high bars and a small tank. Dual instruments replaced the single speedometer in the headlight bucket.
Two thing that you will find on a Norton of this time are the Featherbed frame and a transmission that is not mated to the engine as one unit. The frame was the envy of all other manufacture, and the pre-unit design had long ago ditched by the other makers. The Norton’s seem to have gotten the lions share of blame for the vibrating British twin stereotype, but they also seem to have spent the most time addressing the issue. So when you win this Norton Atlas, do not send it back because you can’t focus your eyes while riding.