J4 Magneto

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whtwolf97
Posts: 22
Joined: Tue Jun 09, 2015 7:32 am
Zip Code: 35757
Tractors Owned: 1949 Cub
1950 Case SC

J4 Magneto

Postby whtwolf97 » Wed Jun 24, 2015 5:10 pm

I wasn't getting any fire coming out of the spark plug wire so I checked the timing, made sure it was correct, and still nothing. Checked the coil wire and got fire going into distributor but nothing coming out. I took a look at the rotor and it looks ok but the pinion gear that drives the rotor has several worn teeth which makes the rotor loose. I figure that my firing problem, am I right about that or has someone got another idea? Should I replace both the rotor and gear or just the gear and see how the rotor does with it? This is a J4 magneto on a 49 Cub. Thanks

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Rick Spivey
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Joined: Sun Jul 01, 2007 10:07 pm
Zip Code: 29681
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Location: SC, Simpsonville 29681

Re: J4 Magneto

Postby Rick Spivey » Wed Jun 24, 2015 7:31 pm

Usually it is fine to replace just the pinion,rotors seem to last longer. That slop could make your timing off or erratic, but shouldn't make it not fire at all UNLESS it is a lot of slop. Definitely needs to be addressed.
Rick Spivey
'52 Cub ("Great Personality") 148xxx
'48 Cub with FH ("Gunny Cub") 38xxx
'57 Lambretta (a slow work in progress)
'74 Triumph TR6 (Mama's toy)


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