Oh Dear .

" I know its slightly different, but when I was a lad working at Nortons, they had a problem with oil consumption in the 750cc vertical twins. The motors were consuming more oil than petrol! So a rig was made so that an engine could be motored by an electric motor up to the red line....around about 7,000rpm. The motor was covered in perspex windows. Using a strobe the inside of the motor could be seen to be apparently stationary. The volume under the pistons was just mist there were no identifiable drops or droplets. It was a very violent place.

One of our engines, at double the rpm, would still be a very violent place, essentially full of mist I believe.

Nortons oil consumption problem was identified as the incorrect finishing of the cylinder bores, once the 45/45 degree honing was reinstated all was well.The motors went back to using more petrol than oil, just. Incidentally it was out of this experiment that the "Superblend" main bearings were specified. At high revs the three piece crank was seen to be flexing(!!) and significantly reducing main bearing life. Just goes to show the sort of R & D that has to go on when a motor is increased in capacity by 50% and power doubled. "

Bill Pudney
Adelaide, Australia


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