- Mon Mar 18, 2013 9:49 am
#23178
Can't help with the number of teeth but I suspect the ratio will be 2:1. Perhaps someone will have their magdyno on the bench and will be willing to count them! Magnetos are normally made clockwise or anticlockwise, and, as far as I know, can't be changed. The armature, magnets, points, and the pickup and earth brushes are positioned relative to each other to provide the biggest spark when the points open and if the magneto was run in the wrong direction this wouldn't happen.
The dynamo question is much easier. Lucas dynamos can be used either as positive or negative earth and can rotate in either direction. After the battery has been fitted, a lead is connected to the 'live' terminal - this will be the positive terminal on a negative earth system and the negative terminal on a positive earth system. The other end of this lead is touched briefly two or three times to the (unconnected) F (field) therminal on the dynamo. This 'polarises' the field coils to suit the earth system being used. A mechanical control box will work with either earth system. An electronic one, however, has different internal components for the two earth systems so can't be altered (they're usually switchable between 6 and 12 vols systems easily, though).
