Antique Engines and Old Iron
[Home] - [HELP] - [Forums] - [Library] - [Photo Gallery] - [Groups] - [Classified Ads] - [Subscribe] - [Links] - [Books] - [Sponsors] -

Go Back   SmokStak > SmokStak® Antique Engine Community > Magnetos, Ignition Coils and Spark Plugs
Forgot Password? Join Us!

Notices

Magnetos, Ignition Coils and Spark Plugs Discussion about magnetos, buzz coils, spark plugs, ignitors and low tension coils.

Magnetos, Ignition Coils and Spark Plugs

H-D magneto (Harley Davidson)


this thread has 29 replies and has been viewed 14783 times

Reply
 
Thread Tools Display Modes
  #1  
Old 03-13-2008, 07:34:50 PM
KeithW's Avatar
KeithW KeithW is offline
Registered-III
 
Join Date: Jun 2005
Location: North Las Vegas, Nevada USA
Posts: 1,104
Thanks: 16
Thanked 224 Times in 160 Posts
Default H-D magneto (Harley Davidson)

Hello all,

Helping a friend with his latest find. A 1960 Harley Sportster with the magneto ignition. What an odd duck. Normally you would expect a twin magneto to fire every 180 degrees. Since this is a 45 degree V twin number one fires then the other fires 22.5 degrees short of 180 degrees later. Then of course the other fires 180 plus 22.5 later. The way I normally time mags is with an o-scope. I adjust the points to open at the peak of the coil voltage curve. This gives the hottest spark and works quite well. On this mag the coil pulses are spaced 180 degrees apart but the point opening events are not. This means they cannot both line up at the peaks. Either one spark is really great and the other weak or the other way around. I ended up splitting the difference and the spark is pretty good on both. I really can't think of any practical way to build the magneto to allow for this odd timing arrangement.

keithw
Reply With Quote
Sponsored Links
  #2  
Old 03-14-2008, 03:38:16 AM
The Engineer's Avatar
The Engineer The Engineer is offline
Subscriber
 
Join Date: Apr 2006
Location: Christchurch, New Zealand
Posts: 283
Thanks: 183
Thanked 93 Times in 62 Posts
Images: 24
Default Re: H-D magneto


this may help explain it took me ages to work out how the system worked
Reply With Quote
  #3  
Old 03-14-2008, 09:59:20 AM
Stephen Girouard Stephen Girouard is offline
Registered-III
 
Join Date: Jul 2007
Location: South Louisiana
Posts: 501
Thanks: 174
Thanked 70 Times in 49 Posts
Default Re: H-D magneto (Harley Davidson)

i'm not sure about the mag. model but on all distributor models both cylinders fire at the same time, one just inefectively on the exhaust stroke. the other at its correct fireing angle.. and the two were afew degrees apart, on the lobe which opened the points one lobe was wider (longer duration) than the other. One lobe for front cylinder ,one lobe for the back , each fireing both cylinders at the same time. There were other engine manufacturers who also did this with twins , but at the angle of the cylinders on a harley this fireing ofset had to be done .
Reply With Quote
  #4  
Old 03-14-2008, 10:27:23 AM
Stephen Girouard Stephen Girouard is offline
Registered-III
 
Join Date: Jul 2007
Location: South Louisiana
Posts: 501
Thanks: 174
Thanked 70 Times in 49 Posts
Default Re: H-D magneto (Harley Davidson)

it will start & run on 1 cylinder if its timed 180degrees out, but will be underpowered & run on only 1 cylinder. i found this out at 19yrs old with a panhead, it took me and a old tractor machanic a whole day to figure that out. he had some choice words for a harley that day
Reply With Quote
  #5  
Old 03-22-2008, 09:48:48 AM
KeithW's Avatar
KeithW KeithW is offline
Registered-III
 
Join Date: Jun 2005
Location: North Las Vegas, Nevada USA
Posts: 1,104
Thanks: 16
Thanked 224 Times in 160 Posts
Default Re: H-D magneto (Harley Davidson)

We built a test stand with my Ajax electric starter to save three old men from kicking this pig (or is it hog?). Fired right up but ran only on the front cylinder. After lots of hair pulling pulled the mag and went back to the scope. Since the point opening events are not 180 degrees apart and the magneto coil pulses are, I split the differance and put one on the leading side of the pulse and the other on the trailing side. Big mistake. Not enough energy has been built up in the coil on the leading edge. Set one opening at the peak of the pulse and the other on the trailing side. Makes good sparks and runs on both cylinders. With the point gap set at the spec both openings are on the trailing side. With the points closed the coil is storing energy for a short time so it is much more tolerant of late opening than early. This stuff just keeps teaching me new things.

keithw
Reply With Quote
  #6  
Old 03-25-2008, 10:38:16 AM
JoeCB JoeCB is offline
Subscriber
 
Join Date: Feb 2008
Location: Farmington Hills, Michigan
Posts: 559
Thanks: 98
Thanked 339 Times in 175 Posts
Default Re: H-D magneto (Harley Davidson)

Kieth W , you mentioned that you can set up a mag for peek output by using an o-scope. how is this done? Are you hooking the scope to the primary ( low Volt ) side and looking for the volt peek? can you help w/ the procedure?
Thanks

Joe B
Reply With Quote
  #7  
Old 03-25-2008, 05:16:48 PM
KeithW's Avatar
KeithW KeithW is offline
Registered-III
 
Join Date: Jun 2005
Location: North Las Vegas, Nevada USA
Posts: 1,104
Thanks: 16
Thanked 224 Times in 160 Posts
Photo Re: H-D magneto (Harley Davidson)

http://members.aol.com/keith0alan/images/magneto.jpg

Start by figuring out the proper direction to turn the mag and hooking up a battery drill or something to turn it. Unhook the coil primary from the points. The primary lead feeds channel one on the scope. Leave the secondary lead unhooked. It will generate enough voltage to get your attention but not enough to hurt it's self. Hook a 10k ohm resistor to the points and a 12v battery. When the points are open they will have 12v on them and when they are closed there will be zero volts. This goes to channel two on the scope. The resistor and battery are required to provide a way for the scope to see the points opening and closing.

When you spin the magneto channel one will show a posative and a negative pulse each revolution. Channel two will show when the points open and close. You normally want the points to open when the coil voltage is at it's maximum. On my Ajax mag (American Bosch) that was at the peak of the negative pulse, the posative pulse was not used.

If you can't align the points opening with the peak then a little late is better than a little early. With the points closed and the magnetic field collapsing energy is stored for a short time.

On the Harley (a F-M magneto) with the points set at factory specs the points openings happened after the peak on both pulses. I adjusted them so they opened at the peak of one and after the peak of the other. (non-semetrical firing v twin). On an engine that fires evenly like a vertical twin the point openings can be aligned with both pulse peaks.

Let me know if I missed anything.

keithw
Reply With Quote
  #8  
Old 03-25-2008, 07:27:21 PM
JoeCB JoeCB is offline
Subscriber
 
Join Date: Feb 2008
Location: Farmington Hills, Michigan
Posts: 559
Thanks: 98
Thanked 339 Times in 175 Posts
Thumbs up Re: H-D magneto (Harley Davidson)

Thanks, Kieth
Makes sense, The scope will show the secondary peek and the points opening. Next time I'm messing arount with one of my motors I'll try the O- scope.
Joe B
Reply With Quote
  #9  
Old 03-25-2008, 08:22:07 PM
KeithW's Avatar
KeithW KeithW is offline
Registered-III
 
Join Date: Jun 2005
Location: North Las Vegas, Nevada USA
Posts: 1,104
Thanks: 16
Thanked 224 Times in 160 Posts
Default Re: H-D magneto (Harley Davidson)

You're looking for the primary peak with the scope. What goes on in the secondary is real magic. Can you say "shock excited LC resonant circuit". If you want I can explain it but it takes a little while.

keithw
Reply With Quote
  #10  
Old 03-26-2008, 09:50:54 AM
JoeCB JoeCB is offline
Subscriber
 
Join Date: Feb 2008
Location: Farmington Hills, Michigan
Posts: 559
Thanks: 98
Thanked 339 Times in 175 Posts
Default Re: H-D magneto (Harley Davidson)

Kieth... Sure, let's go for it! The mysterious process that produce that 15 K V from out of "nowhere" has always intriguied me.
Joe B
Reply With Quote
Reply

Bookmarks


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
Harley Davidson Stationary engine grassfarmer Antique Gas Engine Discussion 24 08-28-2018 06:03:29 PM
Harley Davidson engine Benny Mckheean Antique Gas Engine Discussion 2 11-17-2005 08:13:25 PM
Harley Davidson engine value Benny Mckheean Antique Gas Engine Discussion 3 09-28-2005 03:04:58 PM
harley-davidson mod cg gasenginenut Antique Engine Archives 4 06-11-2002 02:15:17 AM
V-TWIN Harley Davidson engine Mark Congden Antique Engine Archives 5 11-14-2000 07:16:21 PM


Use "Ctrl" mouse wheel to change screen size.
All times are GMT -4. The time now is 01:44:34 PM.

Smokstak and Enginads site search!


All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark - A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2016 by Harry Matthews P.O. Box 5612 - Sarasota, FL 34277