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How to upgrade ignition to Dyna Coils 3.0

Discussion in 'The Garage' started by armyofda12mnkeys, Oct 7, 2019.

  1. Hey all,
    I have been letting my 1978 XS400 sit for a couple years and thought I need to get it up and running before the weather turns too cold :).
    It probably already runs (will find out soon when I get my new battery), but I do like to give myself a little project each year to upgrade the bike.
    This year I'd like to upgrade the ignition. I have some Dyna Ignition coils lying around that I never used.
    Believe it is the ones that look like these (vs the other Dyna green ones I see online as well, hopefully i got the correct style :) ):
    https://www.dimecitycycles.com/dyna-single-output-3-0-ohm-mini-coils-pair-dc3-2.html

    I assume the left side goes to the spark plug ... the right side is what I'm not sure about (those 2 metal flat connectors coming out)...
    How will that hook up into the usual ignition hookup? Do I have to jerry-rig something?,
    like take my old ignition coil cut out the connector and splice in something that connects to the ignition?
    Note: I see some red connectors in the pic attached, maybe those are used to connect to the flat metal part? I dont think those came with my coils so I'll have to buy them if so.
    Maybe someone already has done this upgrade and can post a pic.

    Thanks!,
    Ari

    P.S. my bike is upgraded from points to electronic ignition.
     

    Attached Files:

  2. XSLeo

    XSLeo XS400 Junkie

    Your plug wire goes on the post sticking out the top. The two flat blades are the primary side.
    Instead of cutting up the old coils I would make some new wires. On one end install connectors that will plug onto the coil. The other to plug into the bike harness as the stock ones did.
    Remove one coil at a time. Install new coil. May have to build adapters to fit coils to mounts. Plug new wires in where old were.
    repeat on other side.
    If your bike has points then those coils won't work with out some heavy duty resisters. Like older cars used between points and coil. One for each side. Points coils need about 4.5 to 5 ohms primaries.
    If you have an electronic ignition then those coils will probably be ok. The stock TCI used needs 2.5 ohms coil.
    The Pamco after market ignition uses 2.5 ohms coils.
    Leo
     
  3. XSLeo

    XSLeo XS400 Junkie

    Just thought, Do you know for sure just what the coils you have, have as a primary resistance? easy to check, just ohm them out with your meter.
    Leo
     
  4. Hey XSLeo, Thanks for your response... I converted my bike a while back to electronic ignition.
    I think mostly I swapped in a 81 XS400 engine I had lying around (instead of converting my 1978 engine directly to electric), and did some minor wiring harness changes to make it work and used the 1981 Ignition Coils to go along with the engine (did this almost 10 years ago).
    So thinking/hoping the new coils will work.
    I'll get my new battery tomorrow and I'll test it out.
    Thanks for helping out btw.
    PS you can see the current ignition coil setup used here:

    I wonder if I can find the 'connector part' to connects to the current wiring without resorting to cutting up my current coil. (and what the electrical part would be that connects to the 2 flat pieces on the other end). I can solder something up, just may need help on what parts to get for both ends.
    Also Im fine just zip-tieing the new ones onto the frame without any new mounting mechanism.
    I don't *think* they need to be grounded themselves (at least when i asked a few peeps many years ago hehe).
    Adds a little bit of a Mad-Max-ness to the bike :).
    On a sidenote, Here's my bike (added an XS750 tank a few years ago after my Norton Manx fiberglass tank died ... At some point I might try to get a '77 square tank can see if I can modularly swap out both tanks depending on my mood hehe):
    https://live.staticflickr.com/7663/16928253169_a8f1141d9a_b.jpg
     
    Last edited: Oct 7, 2019
  5. xschris

    xschris a lifestyle not a trend Top Contributor

    Stock 80-82 sohc xs400 tci coils used 3 ohm primary and 8.6 secondary.
     
  6. XSLeo

    XSLeo XS400 Junkie

    The coils should be mounted solid to the frame, helps dissipate heat. Keep your coil cool helps it last longer.
    If any paint or plastic on the coil mounts should be stripped to bare metal. The mounts should be too. This provides a good path for heat transfer.
    Leo
     
  7. BBS360

    BBS360 XS400 Guru Top Contributor

    Check out this page:
    http://www.cycleterminal.com/250-connectors.html#SC250
    Should be able to match up the connector with the photos and dimensions. The tricky part is crimping properly.
     

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