Hi,
I need your help regarding my Lucas M01 magneto which is used in my BSA B31 model.
I would be grateful if anyone can help me know the ohmic value of the primary and secondary windings.
My magneto shows about 0.5 ohms in the primary and 3.9 k in the secondary windings. Are these values ok.
Thanks
Hello Abhi,
It shall be right.
I did measured mine recently and values were close to yours.
Condensectomy Booklet.pdf https://share.google/UZOHDRDwsdzq465Gw
Here I have considered in my case to be right values seeing similar on the picture notes from other armature.
Dan
Do you have a spark..? 0.5 Ohms seems low, and hard to measure with a multimeter.
Have you measured with the points open and points closed..?
A 12v Ignition coil would give 4 ohms on the primary, which allows 3 Amps when the points are closed.
Quote from: scifi on 24 Jun, 2025, 08:54 Do you have a spark..? 0.5 Ohms seems low, and hard to measure with a multimeter.
Have you measured with the points open and points closed..?
A 12v Ignition coil would give 4 ohms on the primary, which allows 3 Amps when the points are closed.
It's a magneto not an ignition coil and points set up.The primary coil winding has a very low resistance and the Lucas test procedure say that connecting 3V across it (2 x D cells) should show a current of around 4A which equates to resistance of about 0.75Ω. Low resistances like this are notoriously hard to measure accurately with a meter.
Hi,
It does give a weak spark.
The bike starts with difficulty.
And the bike goes off in slow speed i.e not idling properly.
Thanks
The magnets on the magneto may be weak.
I have a 1930 Husqvarna, that had a weak horseshoe magnet, that could hardly lift a spanner. The previous owner replaced this horseshoe with two Neodium Magnets, one either side, and it now gives a good spark.
If you look for 'Norfolk Man Cave' videos, he has made a horseshoe magnet re-energiser. It consists of about 400 turns of 7/029 wire, which he energises with a 12v battery, to get some magnetism back into the horseshoe. You got to make sure to get the N and S poles the right way around.
Thanks Idie,
Please guide how do i magnetise the magneto.
Should it be in fully assembled condition. Or should the armature be removed for magnetisation.
Can someone please post a proper procedure to remagnetise the magneto.
Should it be in assembled mode or should the armature be removed ????
The armature must stay in the magneto to act as a keeper. This is a specialist job needing a gassing machine.
"Gaussing"?
It looks like the Lucas M01 Magneto has its horseshoe magnet internal in the casing. This is unlike the magnets which are mounted on the outside of some magnetos, and are held in place by magnetism and two countersunk screws.
Have you removed and cleaned and polished the points..? They need to be spotless, free from any pits and spikes, and not have any oil contamination.
The process of re-magnetising a horseshoe is similar to how you magnetise a screwdriver, just bring it in touch with a strong magnet, which is usually an electro-magnet. A slight tap with a hammer, whilst touching the electromagnet, gives the molecules a jolt and allows them all to align N-S.
Yes the magnets are inside the casing.
The points are clean.
I have replaced the capacitor inside the armature.
But still the bike does not idle properly and starts with difficulty.
I have someone who magnetises the magnets for the audio speakers.
So was thinking about magnetising the magneto.