FMJ Magneto ?

Phil 19 · Aug 20, 2020

I have A WD with FMJ4B3 MAG. My question
is the Drive gear in the middle cap
supposed to move in and out about 3/4 of
an inch. The problem I'm having is with
tractor running it will just die and loose
spark pull off cap and you can spin rotor
with no resistance. What keeps rtor drive
gear locked into timing gear.

teddy52food · Aug 20, 2020

I think there should be a thin snap ring. Look for a groove.

tractorguy2 · Aug 20, 2020

The drive gear is held inside a bushing with a snap ring. Your problem is very common on the FM magneto. What is happening is the shaft is gummed up and is causing the bushing to turn inside the plastic cap. It is an easy repair. Remove the bushing and shaft. Clean up the shaft and lightly oil it. Get some Loctite and coat the bushing with it. Slide the bushing back in the cap making sure the bushing is flush with the inside of the cap. Just make sure you don't get loctite inside the bushing. It will work for years.

Phil 19 · Aug 20, 2020

I saw snap and it is in the groove.

Phil 19 · Aug 21, 2020

Thanks will give that a try

FMJ Magneto ?

Phil 19

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teddy52food

Well-known Member

tractorguy2

Well-known Member

Phil 19

Member

Phil 19

Member

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