chop.it.up..

"This remarkably elegant vintage motorcycle is actually a bit of a mongrel: it’s a Rudge ‘bitsa’ built by Jean-Claude Barrois. This bike has had a chequered life, starting out as a 1928 Soyer—a French brand that produced motorcycles between 1920 and 1935. Like many French makes of the time, Soyer used a variety of engines for their motorcycles, including 
JAP, Sturmey Archer and Chaise. This particular Soyer 07S had a JAP engine but the frame was wrecked, so Barrois built his own frame—and eventually replaced the JAP motor with the 500cc Rudge unit you see here. All unnecessary parts have been removed to make it lighter—including the front brake—and a new quarter-gallon tank has been added, along with a “suicide knee” gearshift." http://www.bikeexif.com/rudge-whitworth