J4 Magneto hook-up question.

The Cub Club -- Questions and answers to all of your Cub related issues.
Forum rules
Notice: For sale and wanted posts are not allowed in this forum. Please use our free classifieds or one of our site sponsors for your tractor and parts needs.
BeeGeezer
Posts: 14
Joined: Fri May 14, 2021 11:42 am
Zip Code: 72958

J4 Magneto hook-up question.

Postby BeeGeezer » Fri May 14, 2021 12:19 pm

I recently rebuilt the magneto and I can't remember which wire goes to the terminal screw on the mag.
The tractor doesn't have a proper wiring harness, only three wires. One of them comes off of the starter terminal which is hot at all times. The posts on the amp meter are hot, but not the ones on the push/pull switch. The other two are not hot. I believe these two are for the generator. Currently, I have two wires that are not connected, on hot one not. My question is, does the hot wire go to the terminal on the magneto? I am a little nervous about connecting this wire as I don't know much about mags. I would hate to mess this up due to lack of knowledge.

Thanks

Mht
Cub Star!!
Cub Star!!
Posts: 408
Joined: Sun Jul 08, 2018 9:02 pm
Zip Code: 27606
Tractors Owned: 1949 farmall cub(building from parts) 1950 farmall cub
1971 David Brown 880 selectamatic
Circle of Safety: Y

Re: J4 Magneto hook-up question.

Postby Mht » Fri May 14, 2021 12:49 pm

No. Don’t connect a hot wire to the magneto. The terminal on the magneto connects to ground thru a switch to turn the tractor off.

BeeGeezer
Posts: 14
Joined: Fri May 14, 2021 11:42 am
Zip Code: 72958

Re: J4 Magneto hook-up question.

Postby BeeGeezer » Fri May 14, 2021 8:28 pm

Thank you. I think I will get a wiring harness and go from there.

k hutchins
10+ Years
10+ Years
Posts: 631
Joined: Tue Mar 27, 2012 5:48 pm
Zip Code: 48843
Tractors Owned: 1948 Farmall Cub
193 plow
1948 snow/grading blade
Woods 59 C3
Cub 144 cultivator
Cub 22 mower
Cub 172 one row planter
Original manuals for all the above
Circle of Safety: Y

Re: J4 Magneto hook-up question.

Postby k hutchins » Sat May 15, 2021 6:28 am

cubwire.jpg


You didn't say if you were working with a 4 position switch or not. I will assume you are. I made new harnesses for both my '48s using the above diagram. I used #10 wire the main wires and #12 for the lights and shut off switch.

Hope this helps, simplest easy to follow diagram l found.
Why is there never enough time to do the job right, but always enough time to do it over. :?:

Gary Dotson
Team Cub Mentor
Team Cub Mentor
Posts: 5090
Joined: Thu Aug 03, 2006 6:20 am
Zip Code: 43358
Tractors Owned: 48 Cub Diesel (Cubota)
53 Cockshutt 20 restored (Shooter)
52 Cockshutt 20 unrestored
47 Leader "B" (Herckie)
49 Leader "D" (Princess)
49 Leader "D" very rough
48 Leader "D" unrestored
Kubota B6200E
Kubota B6200HST
Kubota B8200HST-D
Circle of Safety: Y
Location: OH West Mansfield

Re: J4 Magneto hook-up question.

Postby Gary Dotson » Sat May 15, 2021 6:51 am

The wire to the magneto is simply a kill wire, the push/pull switch simply grounds the mag terminal to shut the tractor off, it will run just dandy with nothing connected to the terminal, on the side of the mag. the mag. kill wire is separate from the main wiring harness. You'll notice it's not included in the diagram posted above. The magneto is totally separate from the tractors main electrical system. A new harness purchase may or may not include that wire, you might have to ask for it.

BeeGeezer
Posts: 14
Joined: Fri May 14, 2021 11:42 am
Zip Code: 72958

Re: J4 Magneto hook-up question.

Postby BeeGeezer » Sat May 15, 2021 7:27 am

k hutchins wrote:cubwire.jpg

You didn't say if you were working with a 4 position switch or not. I will assume you are. I made new harnesses for both my '48s using the above diagram. I used #10 wire the main wires and #12 for the lights and shut off switch.

Hope this helps, simplest easy to follow diagram l found.


Yes, that does help. I think I may use that when I get some lights.

BeeGeezer
Posts: 14
Joined: Fri May 14, 2021 11:42 am
Zip Code: 72958

Re: J4 Magneto hook-up question.

Postby BeeGeezer » Sat May 15, 2021 7:59 am

Gary Dotson wrote:The wire to the magneto is simply a kill wire, the push/pull switch simply grounds the mag terminal to shut the tractor off, it will run just dandy with nothing connected to the terminal, on the side of the mag. the mag. kill wire is separate from the main wiring harness. You'll notice it's not included in the diagram posted above. The magneto is totally separate from the tractors main electrical system. A new harness purchase may or may not include that wire, you might have to ask for it.


I think I am beginning to get the picture. My test light does not light when I test the poles on the switch, no matter which position the switch is in. Shouldn't it, or is that dead wire the ground wire you're speaking of? The switch only has two positions, on/off, and is so old there is no writing on it and the plastic is near about worn completely off. I can't remember if it is in to run or out. I thought a test light would tell me, but I get nothing from either pole with the switch in either position. Burned out switch?
I noted the position of everything as I was taking everything apart, so I am fairly sure I got it all put back together right.
I know the tractor ran, I have used it. It has just been sitting in the barn for years while I have been away working.

Thanks again for your time.

User avatar
Stanton
Team Cub
Team Cub
Posts: 7712
Joined: Mon Jun 22, 2009 6:56 am
Zip Code: 64070
Tractors Owned: 1942 Farmall AV, serial #87025
1947 Farmall Circle Cub, serial #2116
1948 Farmall Cub, serial #46066
Circle of Safety: Y
Location: Lone Jack, MO

Re: J4 Magneto hook-up question.

Postby Stanton » Sat May 15, 2021 8:15 am

There should be a single wire (#12ga or #14ga) that runs from the single prong at the rear of the ignition switch to the side of the magneto. That’s it; totally separate from the wiring going to the light switch knob.
Pull out to run, push in to kill.
Stanton
Image Circle of Safety

BeeGeezer
Posts: 14
Joined: Fri May 14, 2021 11:42 am
Zip Code: 72958

Re: J4 Magneto hook-up question.

Postby BeeGeezer » Sat May 15, 2021 9:14 am

Stanton wrote:There should be a single wire (#12ga or #14ga) that runs from the single prong at the rear of the ignition switch to the side of the magneto. That’s it; totally separate from the wiring going to the light switch knob.
Pull out to run, push in to kill.


Understood, Thank you. I do have a new switch, I think I'll go ahead and change it.

User avatar
Rick Spivey
Cub Pro
Cub Pro
Posts: 2703
Joined: Sun Jul 01, 2007 10:07 pm
Zip Code: 29518
Circle of Safety: Y
Location: SC, Cades 29518

Re: J4 Magneto hook-up question.

Postby Rick Spivey » Sat May 15, 2021 9:04 pm

BeeGeezer wrote:I think I am beginning to get the picture. My test light does not light when I test the poles on the switch, no matter which position the switch is in. Shouldn't it, or is that dead wire the ground wire you're speaking of?


There will be no "power" on the magneto kill wire, it simply grounds the points out to kill the spark. You can test the switch using a continuity test to any good ground location. That will determine that your switch is good or not.
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)

Gary Dotson
Team Cub Mentor
Team Cub Mentor
Posts: 5090
Joined: Thu Aug 03, 2006 6:20 am
Zip Code: 43358
Tractors Owned: 48 Cub Diesel (Cubota)
53 Cockshutt 20 restored (Shooter)
52 Cockshutt 20 unrestored
47 Leader "B" (Herckie)
49 Leader "D" (Princess)
49 Leader "D" very rough
48 Leader "D" unrestored
Kubota B6200E
Kubota B6200HST
Kubota B8200HST-D
Circle of Safety: Y
Location: OH West Mansfield

Re: J4 Magneto hook-up question.

Postby Gary Dotson » Sun May 16, 2021 6:48 am

From your description, it sounds like your 1 prong switch has been replaced with a 2 prong. In this case, one wire will go to chassis ground and the lead to the magneto connects to the other, it doesn't matter which way they are connected. With that set-up, out will be off and in will be engine run position. It works ok that way, just confuses people familiar with the normal, out to run, set-up.

BeeGeezer
Posts: 14
Joined: Fri May 14, 2021 11:42 am
Zip Code: 72958

Re: J4 Magneto hook-up question.

Postby BeeGeezer » Sun May 16, 2021 7:09 am

Gary Dotson wrote:From your description, it sounds like your 1 prong switch has been replaced with a 2 prong. In this case, one wire will go to chassis ground and the lead to the magneto connects to the other, it doesn't matter which way they are connected. With that set-up, out will be off and in will be engine run position. It works ok that way, just confuses people familiar with the normal, out to run, set-up.


Yes, that is correct, I have a two prong switch. You are also correct when you said it confuses people of which I am one. :D
Thanks again.

BeeGeezer
Posts: 14
Joined: Fri May 14, 2021 11:42 am
Zip Code: 72958

Re: J4 Magneto hook-up question.

Postby BeeGeezer » Sun May 16, 2021 5:33 pm

My Cub is now running, so I did a little hilling in the garden. The throttle was not responding correctly, but does seem to be improving on it's own. That may become the subject of another thread, though.

Thanks everyone for your help.

User avatar
Glen
10+ Years
10+ Years
Posts: 5621
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: J4 Magneto hook-up question.

Postby Glen » Sun May 16, 2021 9:27 pm

Hi,
TM Tractor has new ignition switches for Cubs with a magneto, if you want one.
One is Case IH, it says. One costs less than the other.

http://www.tmtractor.com/new/el/605fp.htm

http://www.tmtractor.com/new/el/1176fp.htm

You didn't say the year of your Cub.

Below is a page from Walmart, the 1st switch on the page is like they originally came with, if it serial number 224400 or below, the Cub parts manual shows. :)

https://www.walmart.com/search/?query=54207db

User avatar
Stanton
Team Cub
Team Cub
Posts: 7712
Joined: Mon Jun 22, 2009 6:56 am
Zip Code: 64070
Tractors Owned: 1942 Farmall AV, serial #87025
1947 Farmall Circle Cub, serial #2116
1948 Farmall Cub, serial #46066
Circle of Safety: Y
Location: Lone Jack, MO

Re: J4 Magneto hook-up question.

Postby Stanton » Mon May 17, 2021 7:24 am

BeeGeezer wrote:My Cub is now running, so I did a little hilling in the garden. The throttle was not responding correctly, but does seem to be improving on it's own. That may become the subject of another thread, though.

Thanks everyone for your help.


Glad you got it running again. Remember, if you need to take your carb apart for cleaning, after removing the screws, lift the top straight up so you don't break off the idle tube that's connected to it.
Stanton
Image Circle of Safety


  • Similar Topics
    Replies
    Views
    Last post

Return to “Farmall Cub”

Who is online

Users browsing this forum: No registered users and 2 guests