Reply To: Magneto Testing

[sidevalve5]

Hi Andy,

Firstly, none of the multimeter test figures came out of my head. I certainly do not have the expertise to recommend them. A lot came from published material from magneto repair specialists that I have collated and used very successfully on several instruments. I fully agree with you that just finding continuity with multimeter through a coil is not a real test at all. It is the amount of resistance that is important and different coils do indeed have specified different resistance requirements. It is why some manufacturers have published the resistance figures so a coil can be tested with a multimeter by a service engineer.

Have only this last week received some spares from George of Villiersparts, have used him many times. Following your comments I took the time to read what he said on his website’s Ignition page. I contend he actually confirms what I have said and indeed you too. I quote him “If you test one with a multi meter & find a circuit through the windings it still doesn’t mean it will function properly”. He does not mention resistance figures. Do have a lot of time for George, he has helped me out many times with difficult to obtain spares and indeed supplied me with one of his non original cheaper coils for the Villiers engine on the Clifford. It worked an absolute treat.

I wrote my piece in order to help other enthusiasts check, service, repair and improve a magneto themselves at a reasonable cost. The machines we are interested in are not worth a great deal of money, so if they can be kept going with little spent on them, then surely that is to the good. You appear to suggest the only way to properly test a magneto is by using a specialist ignition tester. Am presuming you are referring to a spark test being done under air pressure. A chap working on a vintage pedestrian machine may not want the expense of purchasing one. If such a fellow does not have a multimeter, then one can be obtained for less than £10. Taking a magneto to a specialist will cost a great deal of money, around £300 would be the approximate average. That is prohibitive as a lot of the machines they are fitted to are not worth that as restored runners.

Am very respectful of your vast experience, its very much more than mine. Would really like you to state what is your recommendations for someone with limited skill and budget when they have no, or little spark from their magneto.

Best wishes,

Grahame