Fairbanks Morse FMJ4 Magneto Restoration & Rebuild

Hello all and welcome back! Well, since we have been spending so much time in Rudy's shop lending him a hand - why not do another magneto video! In this segment, we tear down, inspect, clean and rebuild a Fairbanks Morse FMJ4 magneto. These mags are commonly found on Allis Chalmers tractors, as well as some stationary power units that are still in use on jobsites today. I hope you enjoy and please bear with me as I get used to narrating videos. Thanks for watching and wrenching with me - stay tuned!

[@TractorTalesCattleTails]

Thanks for the great video Kenny! Gives me the confidence to go through the old tired mag on our 46 WC. Keep up the good work

[@KennyKizzleRustyNutzRanch]

@@TractorTalesCattleTails glad you enjoyed. Hopefully it helps!

[@1lilfarm]

Awesome! Thanks Kenny!!! Convinced me to leave the FM mag to the experts. 😊😊😊

[@KennyKizzleRustyNutzRanch]

They aren't too complicating, but the key is we have a few special tools to break them all the way down. Without those tools, you'd have a heck of a time!

[@TractorHoarders]

Fantastic work! It sure helps when you have all the right tools. I had never seen a little puller like that. Having the press and right test equipment is key too. Thanks for sharing! Great video!

[@KennyKizzleRustyNutzRanch]

Yessir! Rudy has a lot of interesting tools. Some are specialty tools, some are homemade that he came up with in his mind to help his process. He's very inventive!

[@rodneymiddleton9624]

The magnetos have always been a mystery to me. Thanks Kenny!!!!

[@KennyKizzleRustyNutzRanch]

Not much to them. The older they are, the more complicating and intricate they get.

[@tractorhyatt7044]

Great work as always, Kenny! You are good at explaining what is going on as you do the work. I am glad you are able to get it all on video. Thank you! 🇺🇸🚜👍

[@KennyKizzleRustyNutzRanch]

Thanks, Hyatt. Trying to narrate at the pace of the video can be difficult. I'm getting the hang of it, though!

[@geoffweinstock6846]

Thanks for sharing Kenny. Back in the 70"s my mother would have painted that wound with some good old merurochrome and sent me on my way.....

[@KennyKizzleRustyNutzRanch]

'Tis but a flesh wound! It probably looked worse than it is.

[@Pete-ln4vu]

Nice job Kenny!! You and Rudy Do Awesome Work!!

[@KennyKizzleRustyNutzRanch]

Thanks, Pete!!

[@leeharris3061]

Nice jab to your hand with the pick ouch!! Cool video to see the insides of one of them..the sparks from that test look nasty..zap zap👍🏻

[@KennyKizzleRustyNutzRanch]

Meh, it's only a flesh wound. Ha ha. My hands are mostly scar tissue anyhow. One more won't hurt.

[@jamesdiehl8690]

You and Squatch Senior do great rebuild vids! 😀

[@KennyKizzleRustyNutzRanch]

Wow thanks!!! To even be mentioned in the same sentence as Senior is an honor!

[@jamesdiehl8690]

@Kenny Kizzle Rusty Nutz Ranch you work on those things all of the time! You do a great job and you explain the procedures just like Senior. I watched him rebuild one and the carb for the D2! You both could right your own repair manuals! 😀😃

[@randycornell9796]

That was interesting!! It's always nice to learn something, even though I probably will never need to do that.. Stay safe my friend.🤓👍🤓👍Randy.

[@KennyKizzleRustyNutzRanch]

Glad you enjoyed. I'm doing a few of these magneto videos by request. Don't worry, there will be more engine and tractor videos coming!

[@bryanh1944FBH]

Yeah, I enjoyed the video! I tell you what, somebody is going to be real happy with that magneto!

[@KennyKizzleRustyNutzRanch]

I think I'll agree with you on that statement!

[@inthelandofmilkandhoney457]

Awesome Kenny 👍

[@KennyKizzleRustyNutzRanch]

Glad you enjoyed!

[@171apples171]

This is an awesome video man, thank you. Im working on some Wisconsin Twin motors and i want to be sure the magnetos are clean and lubricated before any run time on an engine. Now i know what i might be getting into lol

[@KennyKizzleRustyNutzRanch]

You're very welcome! I am glad it gives you some insight as to where to head. Worst case scenario is you get stuck and end up sending it to us at Rebuiltmags.com!

[@171apples171]

@@KennyKizzleRustyNutzRanch id be happy to, that is if i get stuck. the little gear pullers make me nervous lol ill see if i can figure something out. You guys have a great day, thanks again

[@PaulCTownsend]

Great job.

[@seniorelectrician6831]

Thanks for the inside view

[@KennyKizzleRustyNutzRanch]

You are very welcome

[@oldsteamguy]

very helpful. thanks for posting

[@KennyKizzleRustyNutzRanch]

You're very welcome!

[@ihus9950]

👍🏻

[@miltonbristow4470]

Would be interesting to see how you recondition the magnet

[@KennyKizzleRustyNutzRanch]

I can do that!

[@johnnyholland8765]

When you re charge the magnet how long will the new "charge" last? Oh sorry about your hand. That had to hurt...

[@KennyKizzleRustyNutzRanch]

I'm used to it. Lol. My hands are nothing but scar tissue at this point. Magnets typically hold a charge for decades.

[@DwightChafin-l5w]

Great video, can you show me how you recharge the magnets in these mags? Thank you

[@KennyKizzleRustyNutzRanch]

@@DwightChafin-l5w you need a recharging station to do it.

[@evankibbe590]

Always like watching you rebuild a mag 🙄

[@KennyKizzleRustyNutzRanch]

Well. If you don't want to watch it..... Then don't? Lol.

[@cj7fun579]

Is it always best to replace coil with a genuine FM coil, or is an aftermarket coil good enough? I'm having a problem with an FMX Mag on a Lincoln Welder. I've completely disassembled it, replaced everything, Impulse spring, coil, condenser, and points set. The points are gapped to .020" and the mag is timed to the Flywheel at TDC like the factory specs. The engine is hard to get cranked up then finally catches. I have ruled out the carb, spark plugs, and wires, all new. It runs great under a load for about an hour when everything is good and warmed up, but when it goes from low idle to high idle it starts missing bad like pulling the wires off the spark plugs. I pulled the mag off, and checked the spark, and it has a weak arc to it. Is it possible that the coil and condenser being new , go bad after the engine gets hot, and breaking down? Thank You for the video, very professional.👍

[@KennyKizzleRustyNutzRanch]

We have had bad condensors and bad coils right out of the box before. I know that Rudy doesn't use genuine Fairbanks coils, but he does use good coils from a reputable company. Not sure who. If you would like to send your mag to us, we can test it and figure out what exactly is going on! rebuiltmags.com

[@alanharney5278]

Hey Kenny nice work! Mags remind me of my old '56 Triumph. By the way, I went back and looked at the mag on that Oliver HG crawler that I shared on FB and it is a Wico. Is that a common type or unique?

[@KennyKizzleRustyNutzRanch]

Wico are very popular magnetos. A lot of John Deere tractors run Wico magnetos

[@michaellamoureux8105]

i need a rebuild kit for my maneto.its a four cylinder fairbanks morse where do i find this please

[@KennyKizzleRustyNutzRanch]

Contact Rudy at www.Rebuiltmags.com

[@tcmits3699]

Great video, how do you re energize the magnets on the rotor and how would you know whether or not to do it. I'm reinstalling f/ m magneto on Novo 1 cyl engine not hit or miss engine. By placing crank tdc on power stroke how do I set magneto for tdc mag has large helical gear fastened to impulse side with the two dots on face of gear for timing. Do I turn mag past impulse trigger or just before to install or do I have to take off front cover to line up all timing marks. No window like Wisconsin to verify timing marks.

[@KennyKizzleRustyNutzRanch]

The magnets are energized using a magnet charging station. Usually we use a gauge that measures the strength of the magnet, but when we rebuild them we recharge the magnets anyhow. No sense in putting it back together without recharging the magnet. I don't have any experience installing magnetos on those engines - your best bet would be to give Rudy a call at Rebuiltmags.com!

[@michaeldob2153]

Kenny, great vid! Is it the same magneto which you used for your MM ztu? Where can you buy a puller like you used in your video? Keep your great work up!

[@KennyKizzleRustyNutzRanch]

It is very close, yes! I would imagine you can buy a small two jaw puller on most internet sites (Amazon, etc.)... Otherwise keep an eye out at tractor show swap meets. Surely they will be there!

[@Steventhedieseltechapprentice]

Hi Kenny, where can I buy a puller like you used to pull the gear off the magneto? Thanks!

[@KennyKizzleRustyNutzRanch]

I would imagine you could find a small two jaw gear puller on Amazon, eBay, or at most of your automotive to supply stores.

[@jfweimar]

just had mine restored. Got it, hooked up #1 wire w/plug and hand turned. No spark. Is this an acceptable way to test (by yourself)?

[@KennyKizzleRustyNutzRanch]

Are you grounding the plug to the mag body? the plug must be grounded to complete the circuit.

[@chetolikerpurpul]

Where did you get that small gear puller for getting the gear off of the shaft?

[@KennyKizzleRustyNutzRanch]

Rudy has had many of these tools for decades. I have asked him about some of them (the small gear puller being one). He said they are extremely hard to find.. If you find someone looking to sell out of their magneto shop, or look thoroughly on eBay, I am sure one will come up at some point! You could also make one if need be, but you would likely need a mill.

[@pvanb2]

Hi...that coil wire at 5.46...if it is shows as grounded to the magneto case....I suspect internal short in coil ? Is that correct ?

[@KennyKizzleRustyNutzRanch]

The coil wire connects to the distribution block at the end of the points bracket. There shouldn't be any wires grounded to the housing inside the magneto. The ground wire to cut spark to the magneto is connected to the insulated stud that goes through the side of the housing. This is then either connected to a spring steel push button shutoff on the side of the magneto, or to a single pole magneto switch.

[@pvanb2]

@@KennyKizzleRustyNutzRanch Thanks...yes the stud has no connection to ground of the magneto frame, but when the coil wire, primary, I assume, is attached to the spring connection to the points bracket, then the ohm reading is approx 1 ohm. Measuring that wire from the coil by itself, with the coil installed, the same approx. 1 ohm reading (depending on the DVM used, I get a variance from .8 to1.5 ohm reading, discounting and subtracting the ohm reading from just the leads,) Is this correct reading for a primary winding...or is it possible internal short in the primary?

[@pvanb2]

@@KennyKizzleRustyNutzRanch Hi...after removing the FM X4B16A-1 magneto, I see the impulse coupling is damaged. Is their a supplier to source one of these or it's attendent parts?

[@williammundy2704]

Could you tell us what the name of the coupling tool & the small puller with the cutout are? Getting into mag building too, and those look like real time savers! Great videos!

[@KennyKizzleRustyNutzRanch]

The tool to wind the impulse coupling and spring was something we had made. The puller I think you are referring to is a small two jaw puller that has thin jaws. They are very hard to find these days.

[@williammundy2704]

@@KennyKizzleRustyNutzRanch thank you! Could you post a picture so I could get dimensions? Am a machinist. The puller in question looked like a small socket with a cutout and a screw on top as a jack screw, a close up of that one too? A very well made video.

[@landonh5134]

What does this go to I found a new one of these looks all original have no clue what to do with it

[@KennyKizzleRustyNutzRanch]

These were used on a variety of engines. You will find them commonly on older Allis Chalmers tractors.

[@jamesdiehl8690]

Hi Kenny! Haven't seen you on for a while!

[@KennyKizzleRustyNutzRanch]

I'm trying to be on every week!! Ha ha.

[@jamesdiehl8690]

@@KennyKizzleRustyNutzRanch Good! I've been missing your videos!

[@miltonbristow4470]

How much spring tension

[@KennyKizzleRustyNutzRanch]

I usually wind them 1-2 half turns beyond loose assembly. It should have a decent snap to it.

[@miltonbristow4470]

@@KennyKizzleRustyNutzRanch thank you

[@shaggydogg630]

Great video. Would be interesting how the rotor magnets get recharged.

[@KennyKizzleRustyNutzRanch]

We have a recharging station. Essentially, you pass electrical current through two very large windings and it polarizes and magnetizes the magnetic rotor.