rotor magnetism

[Guy_b_g]

I realize that the rotor in the alternator on our bike is supposed to be a permanent magnet type...my question is:

How magnetic are they?

I currently have that cover off (and am refinishing it), but just out of curiosity I took a wrench and touched it to the rotor to check and see how strongly magnetic it is. It is magnetic, but with a very weak field.

Should it be strongly magnetic? Should I be worried that when I finish restoring my bike the alternator will not charge/charge poorly?

[TopCatGr58]

Hey Guy,

Our Alt's use electromagnets for generating power. The ROTOR is just a large metallic structure that helps to break the magnetic fields generated by the electrical circuits, and it's that breaking the fields that creates the Alternating pulses that creates the power. The ROTOR is not supposed to contact any of the electrical components in the ALT. But just passing thru these electrical fields can cause it to become slightly magnetized, but it's just a side affect! The charging power comes from the field and stator coils, and the reg/rect controlling them! SO don't worry about the ROTOR's magnetism.
T.C.

[Guy_b_g]

whew!..

Thanks TC!

I wasn't sure, and didn't see any kind of permanent magnet structure there, but nonetheless it's a relief to know.

[trbig]

To check the coils, with your sidecover back on, you take the thinnest feeler gauge you can find, hold it close to the face ond turn the key on. It will bend the feeler gauge towrds the case, but it's not going to hold a wrench... I'm sure yours is fine.


Tod