Brightspark Magnetos

If you can see the slip-ring through the pick-up hole in the main housing, check that the brass ring or segment of the slip-ring is brass coloured (albeit possibly a bit dirty or tarnished), but not completely black. With twin- or multi-cylinder magnetos, and some single-cylinder magnetos, the brass is a segment, rather than a complete ring, and you may need to rotate the armature in order to be able to see it. If the brass is black, it indicates that the brush(es) are too soft and/or years of neglect.

IMPORTANT. If you haven't already done so, undo the contact-breaker centre-screw and remove the contact-breaker assembly. This disables the magneto to reduce the risk of electric shock and fire.

Wrap some rag around the end of a stick about 1/4" diameter, moisten it with petrol or other cleaning fluid (but not so much that it is dripping), poke it through the pick-up hole in the magneto body, and rotate the armature to clean the slip ring. Repeat with clean pieces of petrol-moistened rag, until the rag comes out clean.

Now let the slip ring dry out with the pick-ups still removed.