In 1974, Don Jones was selling a cast adaptor to fit Yamaha YZ reeds to Honda CR250M. This Cycle Guide article is undated but must be from 1974?
http://www.vintagefactory.com/JonesCR%203.jpgMany other people welded up and machined CR250M cylinders to fit Yamaha reed blocks at the time.
Most peoples "understanding" seems to be that GEM, Mossbarger and Yamaha YZ are "Pre 75 legal" reeds for 73/74 CR250M models. Original GEM, Mossbarger and Jones adaptor kits are almost impossible to find now, but new replica Mossbarger kits are now available from DC plastics, and many have been fitted here in Australia on the understanding that they are Pre 75 legal.
It would be nice if we could confirm their legality ( or not ).
Does anyone have any magazine articles etc from 1974 to support the Mossbarger reeds case?