Possible 1950's Francis Barnett two-stroke
Mystery bike. This was built as a child's special, evidently in France. This is the only photograph I have. The small two-stroke motor is canted forwards, and the spark plug seems to be absent. The chain case has been removed. I believe the tank logo R.Z. is just the builder's name.
It has been suggested that this is a Francis Barnett motor. Certainly the frame is a one-off.