SS , Thanks for that - I suppose I could have pulled both and checked, but with so many suppliers offering special stubs I assumed that something special was needed.
And Chas , yes it was the early 50's 650 T.birds which managed the
90 MPH/MPG feat.
It was 60 odd years ago when I first read the article on the test, but our local old bike mag is rehashing old "Motorcycle" articles(without any acknowledgement) and I had the chance to read it again in a freshened up form.
I still have a clear recollection of the original article, but I cant remember just what I have done with the new mag------.
Adelaide Hills, Australia. 93 R100 GS, 77 R75/7 ,70 BSA B44VS, , 86 R80 G/S PD, 95 BMW Funduro F650 ST