Electronic Ignition Conversion Help

Discussion in 'General' started by DDulin, Jun 14, 2020.

  1. DDulin

    DDulin New Member

    Jun 13, 2020
    Likes Received:
    I recently bought an electronic ignition kit for an early 70’s CT70. The bike only has one black wire coming off the coil under the seat. Someone cut out all the wiring harnesses and just left the one wire. My goal is just to get the bike to run. The kit has several different wires. I’m not sure what wire needs to connect to the black wire on the bike. Also not sure how it needs to be grounded. Does anyone have an idea?
    This is the conversion kit I bought http://www.ebay.com/itm/383514731829
    1970ct70 likes this.
  3. racerx

    racerx Administrator
    Staff Member Administrator

    Jul 10, 2005
    Likes Received:
    If you were already well-versed with the electrical systems of these bikes, you'd not be asking this question. So, for the sake of your own sanity, I suggest buying a new, reproduction, wire harness for your model/year CT70. That way, you can refer to a wiring diagram and know exactly how this gets wired-in. That'd also give you the option of using the keyswitch as your killswitch. The wire harness in the link is for a 69-71 CT70K0 model, it's $30 well-invested...cheap insurance & peace-of-mind. You can simply use only the igntion-related leads, leaving the rest unused. Dratv has other model/years, if this isn't the right one.

    Just to be clear, I'm trying to save you a lot of frustration, by making the conversion process as close to "plug & play" as possible.

    If you want to do this using the existing wiring, follow the manufacturers instructions... hoping they are clear enough, there's enough wiring left in place and you know how to improvise a kill switch. At the minimum, you'll need to connect the exciter lead to the CDI pickup, a primary ignition output lead to the HT coil, a system ground and a switched ground for a kill switch.
    mikejana likes this.
  4. allenp42

    allenp42 Well-Known Member

    Apr 1, 2014
    Likes Received:
    As racerx pointed out, you really do need the wiring kit. It kinda makes it difficult to turn it off w/o a wiring harness and key switch. But since you asked, I penciled up the most common wire colors used for the Malaysian CDI kits that I have seen.

    First of all, you'll need to tape up the ends in the wiring harness that come from the lower coil. The lower coil is the DC charging and lighting coil. Normally, the wire colors are green and yellow but not always. The black/white wire goes to the black wire from the coil, and from what you describe, is the only wire you have on the bike?

    Then you should see 2 wires where the color code of the wires coming from the stator (top coil, usually yellowish) match the color code of 2 wires from the CDI box. You also need to ground the green wire from the CDI.

    I made a rough sketch of how you need to wire it based on the kits that I have seen first hand. However, I have seen a few where the color codes varied a bit.

    Attached Files:

    mikejana and racerx like this.

Share This Page