by Steve J » Wed Dec 21, 2016 7:48 pm
The mag housings are the same for 125 & 150 engines.....however, there are variations on the side of the housing for getting the ignition and lighting wires out through the housing from the stator. If yours is an early D/LD type, the HT winding is built into the stator plate assembly, so there is one connector for the HT lead to the plug, and a separate connector which screws into the mag flange for the lighting output and the ignition cutout connection. Later machines (from around 1956 onwards) with the separate external HT coil generally have a single rectangular connector/terminal block which slots into an aperture in the mag housing, held in place by a single screw. That connector has three connections, taking two connections from the lighting coil, and the LT ignition feed. (There was also an intermediate version which had the external HT coil, but still retained the screw-in connector for the lighting connections and the LT connection to the HT coil.)
If you could identify whether your engine has the separate HT coil or the one built into the stator, that would help.