How to remagnetize a magnetic flywheel?

[SOHC]

I have a bike witch has steel magnets in the flywheel for the CDI ignition and nothing more, I think they are pretty week and the spark was not as good as it could be.

 

Is there any good tricks to remagnetize them? would the old trick of rubbing a strong magnet over them work?

 

I was on youtube one guy was welding right next to a magnet and reckoned that helped?

[Nominal]

I have a bike witch has steel magnets in the flywheel for the CDI ignition and nothing more, I think they are pretty week and the spark was not as good as it could be.

 

Is there any good tricks to remagnetize them? would the old trick of rubbing a strong magnet over them work?

 

I was on youtube one guy was welding right next to a magnet and reckoned that helped?

 

Heating is usually bad for magnets.

[SOHC]

Heating is usually bad for magnets.

 

Yes thats what I thought, he warped it in a wet rag and welded next to it but I also thought electromagnets took away magnetism from steel? we use to use an electro magnet to demagnetize things that had become magnetized from the surface grinders magnetic hold down table     

[Nominal]

^ That could work as it is kept cool, and the welding current (I assume it was electric welding) would induce a magnetic field.

 

Are the magnetic pieces removeable? If so they could be remagnitised with a coil of wire around them and a DC current in the correct direction.

 

I have a demag do-day made from an AC transformer. This works because the current switches back and forward leaving no residual as you move the thing away.

[Nominal]

Seems plausible:

 

To permanently magnetize metal you need to heat the metal past its Curie Point and the allow it to cool within a strong magnetic field.

Items needed:

1. Strong Electromagnetic coil. See http://education.jlab.org/qa/electromagnet_02.html for instructions on how to make one from a car battery.
2. An IRON rod. Different metals require different heat. These instructions assume that you're using iron. (NOT STEEL).
3. A propane torch.
4. Protective gear (fire extinguisher, safety goggles, flameproof gloves, tongs, FIRE EXTINGUISHER, etc)
5. Infrared (touchless) thermometer capable of measuring at least 800C/1500F
Setup

In a room with proper ventilation, with a cement or or other non-flammable floor, setup the magnetic coil. The coil should be large enough for the iron rod to pass through easily without touching. The iron rod will be heated, and that will most likely damage the insulation on the wire. Please keep in mind that the coil may end up being a one-time use item.

Procedure:
Activate the electromagnetic coil. Begin heating the iron rod. It will begin to glow red hot. Using the thermometer heat it well above 770C / 1420F, its Curie point. Once heated, it will loose all magnetic properties. If you were to try and stick a magnet to it, it would simply fall off (and at that temperature, possibly damage the magnet!) Quickly place it within the (activated) electromagnetic coil and allow it to cool within the coil.

You now have a permanently magnetized piece of iron.

I've read other answers that indicate you can rub a magnet on iron, or just put in an electromagnetic coil, but these only temporarily magnetize the item. A degaussing coil or strong magnetic field will disrupt them. The key here is heating to the Curie point..very important.

PS - this will not be as strong as Neodymium or 'rare-earth' magnets. Those are made by compressing tiny inherently magnetized particles and then coating them to keep them intact. But it should stay permanent even in the presence of other magnetic fields.

 

Source(s): http://education.jlab.org/qa/electromagnet_02.html
http://www.howeverythingworks.org/page1.php?QNum=1109
http://www.youtube.com/watch?gl=ES&hl=es&v=X8ZHQQUusGo

[SOHC]

[SOHC]

I understand they are hardened steel magnets, and have had some kind of hardening process? 

[RUNAMUCK]

Sheepers would be the man to ask about magnets.

He knows so much about them that ferrous objects are attracted to him