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Ian Parsons

I would question Roger’s comments on Scott’s published power outputs being fiction and his estimates. I have drawn a graph of a number of motorcycle power outputs and the mean maximum speeds given in the motorcycle press road tests. Most of this information is from tests in the ’50’s and ’60’s. If you accept that the frontal area of most bikes with a rider is similar and that they are correctly geared then there is a very good correlation between power and maximum speed. From this you can determine the approximate power of a bike from its max speed or vice versa.

If I could work out how to insert an Excel graph I would include it here.

However here is some data from the graph
33bhp 95mph
30bhp 90mph
24 bhp 80mph
20bhp 75mph

I have been timed at the following speeds on Scotts at the end of a SS Kilo
498 Short Stroke Flyer 72mph
The same bike with a DPZ engine 84mph
596 Sprint Special 94mph

This would imply that Scott’s published power figures are quite realistic and possibly they have a slightly lower frontal area than the average bike of the post war years.

I await further comments with interest. I am certain that quite a few Scotts with 596 RY or PY engines are good for the low to mid 90’s