1974 Norton 500 BSA Isolastic
1974 Norton 500 BSA Isolastic
A works bitza
Norton, which had merged with BSA/ Triumph in 1974, had only one model in its catalogue at the time – the Commando and little money to develop a new model.
NVT Raids the Organ Bank
But the new Norton-Villiers-Triumph Group had a large “organ bank” at its disposal and took over the studies initiated by BSA into Wankel rotary engines. It prepared for the near future with this odd prototype based on the final version of the 500 BSA Shooting Star.
Crazy Logic
There was a sort of crazy logic about the concept, for while the Beeza engine was still extremely competitive, it vibrated alarmingly. Norton had developed a frame for the Commando with flexible engine mounts to insulate the rider from such undesirable phenomena. Putting the two together seemed the natural thing to do. Bob Trigg, one of the “fathers” of the “Isolastic” frame, was put in charge of the project and created this works bitza, which used BSA/Triumph brakes and suspension parts. The NVT group’s dismal lack of finances meant that the project was never satisfactorily concluded. NVT preferred, in 1975, to try a desperate act of bluff designed to attract investors, and thus got diverted into an illogical escapade with Cosworth and rotary Wankel power units. Thus NVT missed the boat and lost the chance of saving itself from crisis. So in 1978, Norton announced that it was going into liquidation and Yamaha enjoyed world success by putting four-stroke singles back in fashion with the 500 SR.
SPECIFICATIONS
Engine: 441cc (79×90mm) air-cooled single cylinder four-stroke
Power Rating: over 30 hp
Valves: overhead
Fuel System: carburetor
Transmission: 4-speed, chain final drive
Suspension: telescopic forks (front); swing arm with twin spring/dampers (rear)
Brakes: twin leading shoe drums (front & rear)
Wheels: 19 inch wire (front & rear)
Weight: 375 lb
Maximum Speed: 112 mph
Modern and sporty for Its day, the Norton/BSA had a curious paint job with alternate light/dark fins on the cylinder to camouflage its origins.
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