I am currently in california and fiddling with my G15 Matchless, this has the same ignition points housing behind the cylinders as the Atlas and early commandos. I fitted a second hand boyer that I had run successfully on a later Commando with the points in the timing cover. When I fitted and wired up the boyer I got a good spark at both plugs when earthed to the cylinder head, however when I started the bike it would only run on the rght cylinder. This trip I cleaned the carbs and tried again, this time I was only getting a weak and intermittent spark. I removed the domed cover on the points housing and observed that the rotor seemed to be very clse to the trigger plate and when I removed that I found that the rotor had been rubbing on the soldered connections and had earthed the system. It turns out that the shaft that drives the points cam, onto which the rotor is now fitted can move in and out a bit, it was thus initially touching the highest blob of solder and earthing that but triggering the other circuit allowing the right cylinder to fire. The coils being wired in series allowed both plugs to fire giving the impression that both left and right systems were in good order. Today I filed down the solder blobs and fitted a thick paper gasket behind the trigger plate and the bike is now running correctly on both cylinders.
What I learned from this is that the distance between the rotor and the housing where the trigger plate sits is smaller on these earlier models than on Commandos with the timing cover points arrangement and must be spaced out accordingly.
What I learned from this is that the distance between the rotor and the housing where the trigger plate sits is smaller on these earlier models than on Commandos with the timing cover points arrangement and must be spaced out accordingly.
