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Fairbanks-Morse Magneto

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#1 gamefarmone OFFLINE  

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Posted October 02, 2014 - 10:39 AM

I recently obtained an old Wi. motor (AK series) that has a magneto completely frozen up with corrosion.

  The magneto that came on the motor is a FM J.

  I have a few other FM magnetos off of single cylinder Wisconsins, that have the same # of gear teeth, and that will bolt right up, but are different model #'s.

  Probably a crazy question, but both of my working magnetos have a slightly different rotor shaft shape at the top than my original one does.Would that change the timing of the motor to the point where the magnetos are unusable in the AK?

  I'd have to describe the original rotor as having  a shaft that is half-round with a straight half (where the points close.)

  Looking down from the top, it's like somebody basically took a circle, and cut half of it off.

  The other shafts have the same  round  on half the shaft, with more of an oval shape where the points close.

  Shaft diameters are all the same, and the points Look the same.

  I would just put the old rotor shaft into one of the newer magnetos, but don't think it's reusable due to the pitting/corrosion.

  Outside of buying a whole new/rebuilt magneto, any advice?









#2 boyscout862 ONLINE  

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Posted October 02, 2014 - 11:24 AM

Please post pics to clarify. Look in our Manuals Section. Good Luck, Rick

#3 Bolens 1000 ONLINE  

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Posted October 06, 2014 - 04:19 PM

Not many parts are interchangeable from model to model. What is the exact model of yours?


Still should be able to get parts new I would think.


What part number are you looking for?


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#4 superaben OFFLINE  


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Posted October 06, 2014 - 07:12 PM

I mess around with magnetos quite a bit. 


Tell me what the rest of the model number (after the "J") and then tell me what other mags you have.  I am a Fairbanks Morse dealer and I can check my FM cross reference catalogs for you.


Ben W.

#5 gamefarmone OFFLINE  

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Posted October 07, 2014 - 09:34 PM

Thanks for all of the replies.

  In looking through the old magnetos I've accumulated, I happened to find one that had the same shaped shaft as the damaged one I took out.

  All I had to do was switch out the coil pack, as the points and condenser were good.

  After bolting the new used magneto up and timing it right, the old motor fired right up.

  Ben W., the diagram you posted has exactly the right shaped top of the shaft I needed.

  The other ones I have are the same length, etc., but the top of the shafts are tapered back on each side.

  I'll try to post pictures and model #'s soon, as my descriptions are probably confusing.


                                                                                                                                                Thanks again,