I`ve had Harry Woolridge`s book `SpeedTwin and Thunderbird Bible` for a while now and it`s a real source of inspiration . Lots of detailed technical info. plus those artists renderings they used to use for advertising .
A couple of pictures in it really grab my attention , though . In the section dealing with the `47 Speed Twin , there`s two shots of a bike which it says was customised by Johnson Motors .
The caption just says it`s what JoMo told the Meridan factory they should do to improve the design.
I had to make do with just enjoying the pictures , until I found this;
and more specifically these pictures and info.