classic motorcycle forum

Does anyone know the correct spark plug to use in a Villers Junior engine?  I had originally assumed that the Junior and Junior Delux were largely the same, but on closer examination, my Junior engine takes a 14mm plug whereas the Junior Delux uses a 18mm plug.

Also, can anyone recommend a website selling parts for the Junior engine? There seem to be several sites selling stuff for the Junior Delux but not for the Junior.

And finally, on a similar theme, are there any sites out there with maintenance/repair information on the Junior engine? Again, I've found several sites with PDF copies of servicing information relating to the Delux, but nothing for the Junior.

Thanks in advance