48 cub wont start

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Waif
501 Club
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Joined: Thu Aug 25, 2016 1:29 pm
Zip Code: 49343
Tractors Owned: 48 Farmall Cub "Seen Yore Dobbin"
53 F-Cub W/Loader.
Circle of Safety: Y
Location: Michigan

Re: 48 cub wont start

Postby Waif » Mon Oct 01, 2018 10:19 am

IHS1492.jpg

IF your Cub is in stock configuration for a J4 magneto , your coil is under a cover like this one.

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Glen
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Zip Code: 00000
Tractors Owned: 1956 Farmall Cub with Fast Hitch, F-11 plow, Disc, Cultivator, Cub-22 mower
Circle of Safety: Y
Location: Wa.

Re: 48 cub wont start

Postby Glen » Mon Oct 01, 2018 6:03 pm

Hi,
The wiring diagrams are different for a Cub with a magneto, or a Cub with a Battery Ignition unit. Use a wiring diagram for the equipment your Cub has.

The original style magneto coil is under the cover on top of the magneto, like Waif posted above. It is a special coil for a magneto. The magneto is not connected to battery power, it makes it's own power.
The ignition switch grounds the magneto, to shut off the engine. That is what the wire on the side of the magneto is. Do not connect it to battery power.

The Battery Ignition unit coil is cylinder shaped, like cars used to have. The coil for it is connected to battery power, when you turn the ignition switch on.

I'm not sure about the generator bushing, it would probably be better if it had the notch, like the original. :)

jsdorn
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Zip Code: 18969

Re: 48 cub wont start

Postby jsdorn » Thu Oct 04, 2018 8:43 am

Is the field of the generator magnetized? Mine is not.I seen on youtube that it is magnetized.Is that correct?

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Glen
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Tractors Owned: 1956 Farmall Cub with Fast Hitch, F-11 plow, Disc, Cultivator, Cub-22 mower
Circle of Safety: Y
Location: Wa.

Re: 48 cub wont start

Postby Glen » Thu Oct 04, 2018 4:38 pm

Hi,
Jim Becker might know that about the generator. You could send him a PM, at the top of the page.
Or click on his name at a post he has made, and you can see there how to send him a PM. :)

Jim Becker
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Re: 48 cub wont start

Postby Jim Becker » Thu Oct 04, 2018 10:10 pm

Polarizing a generator sends current through the field coils, creating a magnetic field through the generator frame. The residual magnetism is what you get out of polarizing it.

jsdorn
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Zip Code: 18969

Re: 48 cub wont start

Postby jsdorn » Mon Oct 08, 2018 1:13 pm

neither diagram shows a cub with a Magneto can anyone show me a diagram that shows a Farmall cub with a Magneto a regulator a generator and a kill switch to ground the magneto?

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Glen
5+ Years
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Posts: 2770
Joined: Mon Mar 19, 2012 7:33 pm
Zip Code: 00000
Tractors Owned: 1956 Farmall Cub with Fast Hitch, F-11 plow, Disc, Cultivator, Cub-22 mower
Circle of Safety: Y
Location: Wa.

Re: 48 cub wont start

Postby Glen » Mon Oct 08, 2018 6:45 pm

Hi,
The upper wiring diagram I posted on page 2 of this post shows the wiring a 1948 Cub originally came with. It just does not have the magneto in the pic. The magneto only has 1 wire from the post on the side of it, to the ignition switch, which has 1 post for a wire. The switch grounds the magneto to stop the engine.
Cubs up to serial number 115403 originally had a Relay on top of the generator, it is not a voltage regulator. The voltage regulator came out in mid 1950, at serial number 115403.

It would help if you would identify what the Cub has, a Relay has 3 wire connections on it, a voltage regulator has 4 wire connections.
Can you post pics of the Relay on top of the generator, from 2 sides of it, showing the connections.

With a Relay, you have to select the charge rate yourself. It has to be used with the 4 position light switch that they originally came with.
Below are pages from the 1949 Cub owner's manual telling about the 4 position switch, beginning at the lower left on the page.

http://farmallcub.com/rudi_cub/www.clea ... age-34.jpg

http://farmallcub.com/rudi_cub/www.clea ... age-35.jpg

Some people have changed the original Relay to a voltage regulator, made to go on top of the gen, so it could have that. IH did not use a voltage regulator on top of the gen.

jsdorn
Posts: 23
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Zip Code: 18969

Re: 48 cub wont start

Postby jsdorn » Tue Oct 09, 2018 3:51 pm

What should my generator read I just installed a rebuilt generator.I only get 1.7 volts.it is supposed to be polarized to positive ground.What should I be getting

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Rick Spivey
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Re: 48 cub wont start

Postby Rick Spivey » Tue Oct 09, 2018 6:00 pm

If its a 6 volt generator, I would say from 6.2 - 7.0 volts, and i've even seen up to 9. If 12 volt, something higher than 12 up to 14 or so.
Rick Spivey
'52 Cub ("Great Personality") 148xxx
'48 Cub with FH ("Gunny Cub") 38xxx
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jsdorn
Posts: 23
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Zip Code: 18969

Re: 48 cub wont start

Postby jsdorn » Wed Oct 10, 2018 12:24 pm

I got my cub to start I purchased a new 6 volt battery and when I shut the cub down it does not restart because when I check the voltage at the battery while pulling the starter I get a 2 1/2 volt drop what would cause the the voltage drop?Also can I check the generator with removing the cables.

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Glen
5+ Years
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Posts: 2770
Joined: Mon Mar 19, 2012 7:33 pm
Zip Code: 00000
Tractors Owned: 1956 Farmall Cub with Fast Hitch, F-11 plow, Disc, Cultivator, Cub-22 mower
Circle of Safety: Y
Location: Wa.

Re: 48 cub wont start

Postby Glen » Wed Oct 10, 2018 8:25 pm

Hi,
All 4 battery cable connections need to be in good condition, and clean. Dirty connections are common, and can slow down the starter. Sand them one at a time, so they are shiny metal, wipe off all sanding with a clean rag.

6 volt systems use bigger wiring than 12 volt systems.
If you have 12 volt battery cables, from an auto parts store, they are probably too small, and won't carry enough power to the starter.

Below is a listing at TM Tractor showing the battery to starter cable for the 6 volt, positive ground system. They are made the length to go in the original routing.

http://www.tmtractor.com/new/el/2581fp.htm

Would you post how many connections the unit on top of the generator has, like I asked before. :)

Below is a page from the 1955 Cub owner's manual showing the routing of the battery cables.
The pic shows Battery Ignition, and magneto ignition.
The pic shows the voltage regulator, which is mounted beside the generator, don't use the wiring diagrams for that, if you have the Relay on top of the gen.

http://farmallcub.com/rudi_cub/www.clea ... e%2049.jpg

If you have number 2 or larger battery cables, with good clean connections at the ends, then the problem could be the starter bushings and brushes might be worn. If the bushings wear enough, the armature can rub inside the starter, and that causes slow starter speed, and more power draw.

Jim Becker or others on here have said not to remove battery cables when the engine is running, to test the generator output, it can damage the generator.

The Relay is polarized by touching a length of electrical wire between the Bat and Gen connections on the Relay, for 1 second or so. There should be a spark seen while touching the wire on the connections.
Do not touch the Field connection when polarizing.


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