HOME and how to join Forum Open Area General Scott topics Magdyno parts Re: Re: Magdyno parts

#13135
efr215
Participant

Magnetos despite having been around for 100 years or more are still something of a “dark art” to most of us and it seems there are precious few undertakings that have either the equipment and/or the in-depth knowledge to make a good job of a re-build. Therefore entrust such work only to someone with a proven track record.

Before considering a rewind it would worthwhile having the windings checked as they may well still be good.

One major pitfall is the capacitor buried within the armature. The original capacitor was a component that could be expected to well outlive the machine it was fitted to BUT its very construction meant that it had a life-span and one rather less than the 50+ years of even the most youthful of magnetos we meet today. Even a ‘new old stock’ unused OEM capacitor is well past its ‘sell by date’ now and should not be used. What makes matters even more difficult is that there are a very few modern capacitors that can stand up to what is a very onerous task. So make very sure what your repairer is fitting.

If the armature is removed from a magneto for any reason there will be an inevitable loss of 20% or more in the strength of the magnet(s) in the magneto. Do not imagine that a ‘keeper’ will save the day, the loss occurs in microseconds. The magneto on reassembly may well still work but its output will be proportionally reduced. The answer of course is to re-magnetise the unit but this requires an exceedingly large, powerful and expensive re-magnetiser particularly for the more modern magnetic material, how many re-builders have such a unit? I note that there are some people offering an “internal” re-magnetising service but given that the instrument has to be withdrawn before the armature can be replaced and the almost instant losses previously mentioned it is had to see how this method can be more than marginally effective.