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Old 01-01-2011, 08:55 PM   #1
Zeeman
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Default Four cylinder magneto?

Hi all. Just finished a rebuild on a pan with dual plug shovelheads.
Saw a pic a while back of a pan with a four cylinder magneto cap, like this:





This one looks to be from a four cylinder tractor or similar..
Would it be possible to convert this to use with dual plugs?

Thanks.
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Old 01-01-2011, 09:02 PM   #2
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Default Re: Four cylinder magneto?

It was actually a shovel, from this thread:

http://www.jockeyjournal.com/forum/s...neto&showall=1



Can anyone provide info on how this could work with a pan/shovel?
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Old 01-01-2011, 09:03 PM   #3
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Default Re: Four cylinder magneto?

Contact this fellow. Knows a LOT about what can and cannot be done with FM mags.

http://www.magnetoparts.com/index.html
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Old 01-01-2011, 09:06 PM   #4
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Default Re: Four cylinder magneto?

The top picture is probably from a Tractor as you guessed. But a Model A, B, or C mag could be converted easily as well. The Fairbanks Morse mags are all very similar on top. The base comes off for different applications. they are cheap as well, but no advance and kicking through the impulse couplers might be a real bummer. My A with a starter wouldn't even come close to firing untill I put all four couplers in there. No advance could create starting or top end problems. But when you get it to work it'll be cool as hell.


Tim
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Old 01-01-2011, 09:41 PM   #5
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Default Re: Four cylinder magneto?

Quote:
Originally Posted by Zeeman View Post
I

Can anyone provide info on how this could work with a pan/shovel?


I've seen rotors modified, to run dual plugs, by making the tip wider.
But since there is only one coil for the source, wouldn't the spark
take the path of least resistance and only fire one plug ?
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Old 01-02-2011, 01:41 AM   #6
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Default Re: Four cylinder magneto?

Morris sells this single dual plug wire set so you dont need to go rocket scientist now.
http://www.shop.morrismagneto.com/pr...5&categoryId=4
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Old 01-02-2011, 01:45 AM   #7
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Default Re: Four cylinder magneto?

Yeah, I know about the dual plug wires.. just interested to see if anyone had successfully converted a 4 cylinder magneto.
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Old 01-02-2011, 10:41 AM   #8
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Default Re: Four cylinder magneto?

Won't work. Most four cylinder tractor mags fire at 90 degrees apart. If you use the two opposite plugs (and figure out a way to ground out the two unused plugs), you'll get fire at 180 degrees. Problem is that Harleys don't fire at 180 degrees apart. Can't recall the exact number, but it would take a lot of work to make that mag work, with even getting into the necessary base modifications. Look inside a Sporty mag and you can see the irregular spacing between the integral stator coils, magnets, and lobes on the points cam.

I'd love to see the internals of the mag on the shovel.
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Old 01-02-2011, 11:08 AM   #9
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Default Re: Four cylinder magneto?

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Originally Posted by Sporticus View Post
Won't work. Most four cylinder tractor mags fire at 90 degrees apart. If you use the two opposite plugs (and figure out a way to ground out the two unused plugs), you'll get fire at 180 degrees. Problem is that Harleys don't fire at 180 degrees apart. Can't recall the exact number, but it would take a lot of work to make that mag work, with even getting into the necessary base modifications. Look inside a Sporty mag and you can see the irregular spacing between the integral stator coils, magnets, and lobes on the points cam.

I'd love to see the internals of the mag on the shovel.
Scott, I had one of those mags once. The top of the magnet-rotor had one lobe which would break the points once per 360 degree rotation.

Then the shaft continued up and on top of the lobes was a pinion gear. the pinion gear turned a ring gear at a reduction rate of 4:1

This ring gear had a contact in its middle which was connected to the single coil lead, and a contact on its edge which distributed the spark to whichever cap lead it was pointed to at the time.

This would work for a 4 plug harley, if the contacts inside the cap were modified to correspond with the spark needs of the twin
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Old 01-02-2011, 04:03 PM   #10
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Default Re: Four cylinder magneto?

That's all true, but Harley cylinders don't fire 180 degrees apart like a four cylinder tractor (I can't recall the actual numbers). Life would be a lot easier for project oriented types if they did. The base is doable with enough work. I mated a four-cylinder Wico XV (very similar internals to the F-M) to fit my 45. I learned this lesson the hard way and decided to use the Wico body to hide a Harley specific electronic ignition in the end.

I wish I was wrong. The only place you'll find a magneto points cam appropriate to the Harley firing is on a Harley specific rotor. Same goes for the spacing of the magnets on the rotor. Oh yeah, the magnetoparts.com guy has very little patience for people with questions related to putting tractor mags on bikes. Ask me how I know. Great educational site, though.

Scott

Quote:
Originally Posted by F.St.M. View Post
Scott, I had one of those mags once. The top of the magnet-rotor had one lobe which would break the points once per 360 degree rotation.

Then the shaft continued up and on top of the lobes was a pinion gear. the pinion gear turned a ring gear at a reduction rate of 4:1

This ring gear had a contact in its middle which was connected to the single coil lead, and a contact on its edge which distributed the spark to whichever cap lead it was pointed to at the time.

This would work for a 4 plug harley, if the contacts inside the cap were modified to correspond with the spark needs of the twin

Last edited by Sporticus; 01-02-2011 at 04:09 PM.
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Old 01-02-2011, 04:16 PM   #11
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Default Re: Four cylinder magneto?

Quote:
Originally Posted by Sporticus View Post
That's all true, but Harley cylinders don't fire 180 degrees apart like a four cylinder tractor .

Scott

Wouldn't matter when the lobe broke the points. It matters when & where the distributor part up top sends it.

Remember the multi-cylinder mags have only one lobe on the magnet rotor, and fire a 360 degree spark interval. The path is determined by the cap leads & ring gear position.
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Old 01-02-2011, 05:16 PM   #12
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Default Re: Four cylinder magneto?

I posted the close-up photo of the 4cyl magneto set up on the other thread...

Here's a bigger photo of the bike that it's running on.


Does anyone know the owner of this bike and could they get them to chime in on what they did and how well it runs?
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Old 01-02-2011, 05:18 PM   #13
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Default Re: Four cylinder magneto?

Quote:
Sporticus: Oh yeah, the magnetoparts.com guy has very little patience for people with questions related to putting tractor mags on bikes.
Let's be fair, would you ask you butcher if the auto store 2 miles away is any good!!!

But I can see how that Shovel mag works... It's obviously a H-D Fairbanks (or Morris/Hunt with the wrong label) with the right H-D cam, 22.5 degree offset, and the 2 springs HT coil but special dizzi added on top and driven at same speed as rotor, 1/2 engine speed...

Each spring goes to the dizi bit which has 2 isolated "L" brass fingers, timed, my guess, at 90 deg interval, seeing where the leads go.

And distributes each spark to the right cylinder at the right moment, path being 1st spring on coil-1st L finger on dizzy-spark plug 1-earth through head-2nd spark plug -2nd L finger on dizzy-2nd spring on coil, turns 1/2 turn (+ or - the 22.5 degree angle on the cam...) and repeats sequence for the 2 plugs on the other head.

Patrick
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Old 01-02-2011, 06:12 PM   #14
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Default Re: Four cylinder magneto?

Quote:
Originally Posted by thefrenchowl View Post
Let's be fair, would you ask you butcher if the auto store 2 miles away is any good!!!

But I can see how that Shovel mag works... It's obviously a H-D Fairbanks (or Morris/Hunt with the wrong label) with the right H-D cam, 22.5 degree offset, and the 2 springs HT coil but special dizzi added on top and driven at same speed as rotor, 1/2 engine speed...

Each spring goes to the dizi bit which has 2 isolated "L" brass fingers, timed, my guess, at 90 deg interval, seeing where the leads go.

And distributes each spark to the right cylinder at the right moment, path being 1st spring on coil-1st L finger on dizzy-spark plug 1-earth through head-2nd spark plug -2nd L finger on dizzy-2nd spring on coil, turns 1/2 turn (+ or - the 22.5 degree angle on the cam...) and repeats sequence for the 2 plugs on the other head.

Patrick
can you draw me a picture of that ?
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Old 01-02-2011, 06:14 PM   #15
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Default Re: Four cylinder magneto?

zeeman,is your bike a cone motor or generator model?i might have an idea for you
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Old 01-02-2011, 06:14 PM   #16
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Default Re: Four cylinder magneto?

Thats an ingenous way to do it,...im sure that could be done fairly easy but is it just me or is that a fake mag hiding the coils? Any body see a crane hi-4 in the nosecone?
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Old 01-02-2011, 08:14 PM   #17
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Default Re: Four cylinder magneto?

Good point!

Quote:
Originally Posted by F.St.M. View Post
Wouldn't matter when the lobe broke the points. It matters when & where the distributor part up top sends it.

Remember the multi-cylinder mags have only one lobe on the magnet rotor, and fire a 360 degree spark interval. The path is determined by the cap leads & ring gear position.
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Old 01-02-2011, 11:16 PM   #18
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Default Re: Four cylinder magneto?

Quote:
Originally Posted by rigidpanman View Post
zeeman,is your bike a cone motor or generator model?i might have an idea for you
It's a '59 Panhead bottom end with late shovel heads.

Thanks all for thoughts so far.. gets the brain tickin' over..
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Old 01-03-2011, 12:58 AM   #19
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Default Re: Four cylinder magneto?

Quote:
Originally Posted by choptop37 View Post
is it just me or is that a fake mag hiding the coils? Any body see a crane hi-4 in the nosecone?
Sure looks like it.

A similar thread has come up a few times...that bike has been posted before also, but I think this is the first time the fake mag/ E.I. theory has come up.. Let me see if I can link the last incarnation of this question.....

Edit: here is one
http://www.jockeyjournal.com/forum/s...tractor+mag%2A
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Old 01-03-2011, 04:49 AM   #20
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Default Re: Four cylinder magneto?

Quote:
lilbill: can you draw me a picture of that ?
With pleasure!!!

2 bakelite fingers with brass outers so insulated with each other, 4 HT connections (inside) and 4 plug leads (outside)...





Patrick
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Old 01-03-2011, 07:25 AM   #21
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Default Re: Four cylinder magneto?

zeeman,back in the 80`s a friend of mine did what you are doing,he`s running a typical 2 cylinder mag for 2 of the plugs and has a cone style cam cover and he is running points in the cone to fire the other 2 plugs.im not sure if the cam cover is still available from any vendors out there but that is an alternative on the 4 plug system.if you want any more info on this,let me know and ill ask him for details.good luck
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Old 01-03-2011, 12:15 PM   #22
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Default Re: Four cylinder magneto?

Quote:
It's obviously a H-D Fairbanks (or Morris/Hunt with the wrong label) with the right H-D cam, 22.5 degree offset, and the 2 springs HT coil but special dizzi added on top and driven at same speed as rotor, 1/2 engine speed...
exactly! The first mag pictured (agricultural/industrial) will NOT work without a HD points cam/rotor.
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Old 01-03-2011, 05:50 PM   #23
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Default Re: Four cylinder magneto?

Quote:
Originally Posted by thefrenchowl View Post
With pleasure!!!

2 bakelite fingers with brass outers so insulated with each other, 4 HT connections (inside) and 4 plug leads (outside)...





Patrick
ah sooo................ very clever. truely a cunning stunt
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Old 01-04-2011, 01:40 AM   #24
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Default Re: Four cylinder magneto?

Hi, lilbill

Did not quite like the unbalance of these 2 fingers!!!

Since drawn another with just 2 posts for the HT and balanced fingers, shime in if you want to see that as well...

Patrick
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Old 01-06-2011, 09:02 PM   #25
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Originally Posted by thefrenchowl View Post
Hi, lilbill

Did not quite like the unbalance of these 2 fingers!!!

Since drawn another with just 2 posts for the HT and balanced fingers, shime in if you want to see that as well...

Patrick
yeah, i was thinking unbalanced as well but figured a solid disc with a printed circuit or current strips would take care of that. lets see the other version
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Old 01-07-2011, 11:00 AM   #26
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Default Re: Four cylinder magneto?

Hi lilbill,

Here they are:





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Old 01-07-2011, 02:34 PM   #27
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Default Re: Four cylinder magneto?

Almost got this working, dual plug, mag fired electronic ignition for genny shovel.
http://www.youtube.com/watch?v=ZvVnW...e_gdata_player
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Old 01-07-2011, 02:46 PM   #28
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Default Re: Four cylinder magneto?

Quote:
Originally Posted by jahluv View Post
I posted the close-up photo of the 4cyl magneto set up on the other thread...

Here's a bigger photo of the bike that it's running on.


Does anyone know the owner of this bike and could they get them to chime in on what they did and how well it runs?

Nice pic. I guess i'm going to polish my kennedy's...
-Jr
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Old 01-07-2011, 03:50 PM   #29
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Default Re: Four cylinder magneto?

i have a fairbank-morse 6 cyl magneto that will surely work
it will even fit after some small modification on a morris M5 nosecone

it also has an advange retard system !

i will check what type it is .....or you can buy this one
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Old 01-07-2011, 04:36 PM   #30
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Originally Posted by 45chop View Post
Almost got this working, dual plug, mag fired electronic ignition for genny shovel.
http://www.youtube.com/watch?v=ZvVnW...e_gdata_player
trick. what did you use as a donor for the electronic part ?
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Old 01-07-2011, 04:50 PM   #31
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trick. what did you use as a donor for the electronic part ?
It's not on the bike yet so bench tested only. The plug on the left is firing off the mag and the one on the right working off a 1980's electronic ignition upgrade kit for a car. It takes it's trigger from the killwire terminal off the mag. If it works it's going to be killer.
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