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single fire module for a harley magneto


I don't know if it is ethical to mention brand name so, I won't. I saw a msf [ which is a single fire module for a harley magneto. One lead coming out of the mag going in a cylinder shaped capacitor, resitor or whatever it is and 2 leads coming out going to the sparkplugs. I know the purpose is to convert dual fire to single fire. but what is that cylinder shaped thing and how does it switch the fire back and forth?

John Newman Jr.

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I seem to recall a conversion kit that had a split (2 half-width lobes?) points cam and dual points. Each set of points fired its own coil (required 2 coils) and each cylinder fired seperately at the correct time - No wasted spark in the other cylinder. This was quite a while ago and there is probably an electronic version available now. But I have never been a fan of electronic ignition. Had the unit fail and leave me stranded on the side of the highway on two seperate occasions in my bike (1980 FXS) and I retrofitted it to points. I can deal with points on the side of the road. Can't do much with a dead 'black box'.


The single fire module he is talking about is a set up to fire only the cylinder that is comine up to TDC.