The Butterworth Norton
Picture of Butterworth's Swing Valve motor and now being installed in a featherbed frame.
The exhaust valve is conventional and the swing inlet (shaded)
Just swings out of the way! WOW! There are many advantages to this design.
See how many you can work out. Answers next month!
milesm at avnet.co.uk
Updated photo for you
Chassis is from a '56 domi 99 (I bought the frame, swingarm & a manx rear wheel from Norton George, who was a pal of mine) and the engine is a 600cc Butterworth swingvalve - Archie Butterworth was my great uncle. Lots on the 'net about him...