Running a magneto

All ignition related articles
Post Reply
suicideshovel65
Posts: 105
Joined: Wed Jun 01, 2005 3:46 am
Location: Tokyo

Running a magneto

#1

Post by suicideshovel65 » Thu Sep 08, 2005 1:45 pm

Hi all,

Next in the installment of dumb questions:
What is required to run a magneto in my Pan, and what are the benefits of doing this?

1. As far as physical mods, I have heard that the relay mount must be removed, and that shaving fins on the front cylinder is occasionally necessary. (I have seen a picture of a Pan or Knuck running an auto(?) magneto that was of stockier design - removing the need to grind away the relay mount.)
FWIW my engine already has the relay mount ground off.
Any other physical mods required?

2. I'm guessing then that the points are set in the magneto, and the plug wires are run from the magneto lid. What about for twin plug heads - are there 4-wire caps for the magnetos (I have seen a freaky double magneto for shovels)?
3. Is the magneto rotated to advance/retard timing as per the circuit breaker?
4. I have also seen a capacitor available to stop headlight flickering etc - does this also enable a complete battery-less setup, or should I always retain a battery?
5. Does the generator setup remain the same throughout?

Cheers,

S.



dirtydistrict
Posts: 118
Joined: Tue Mar 16, 2004 11:00 am
Bikes: 2010 road king at the moment. Won't last long
Location: CORNAS FRANCE

Re: Running a magneto

#2

Post by dirtydistrict » Thu Sep 08, 2005 5:07 pm

Hi suicide, don't own a magneto but
1- you need to shave fins to get enough room
2- I think that "y" wires exists for that kind of dual plug
5- if you suppress your battery (magneto was used for race to save weight) genny should go the same. My personnal experience of a sportser's friend with magneto is painful: solid leg and "no smoking" required to kick the beast.
Anyway this is a real motor freaker stuff and it looks great

Cotten
Posts: 6911
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois
Has thanked: 100 times
Been thanked: 268 times

Re: Running a magneto

#3

Post by Cotten » Fri Sep 09, 2005 2:47 pm

For "Joe Hunt" (Fairbanks-Morse) style magnetos, you only need to shave fins on '56 and later head castings, but the relay boss must be totally removed. And the mag cap and sometimes the mag body often interfere with the front pushrod cover, requiring grinding.
If these modifications have already been made, then consider that most early mags were for bump-start race use, and there is no provision for retarding them! (I made an adjustable stop for manual twisting of the mag body.)
If you go with a modern unit (with advance) you will not regret that aspect.
One means of running dual plugs is to use a "trigger", which is a second coil also fired by the mag. Since it fires simultaneously, and is also a 'deadspark' system, most find little value to them.
If you could find an auto-advance, single-fire, dual point, four-lead mag that fits in a Pan without lots of destruction of the original hardware, go for it!
Sometimes the capacitors work well, but not really necessary except when you are sitting at a stopsign.
Yes, your generator system stays the same, although a solidstate regulator is in order.

Post Reply

Return to “Ignition”