I owned a Yamaha Franchise during the 70's. At the time average oil consumption was 1 oil to 100 gasoline. Rod bearings were needle roller and crank bearings were ball bearings. Huge amounts of oil were simply unnecessary. Better carbs, needle roller rod bearings and hardened crank pins were probably necessary along with variable ignition timing.


A 125cc would turn in excess of 11,000 RPM. We had transmissions to get the engine on the curve.