New wiring Harness for K0?

Discussion in 'Tech Area' started by Waveraider, Jan 20, 2012.

  1. Waveraider

    Waveraider Member

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    I need to replace the wiring harness on my 1970 CT70, but I'm thinking about getting a Lifan 88cc engine in about a year. Can I just buy a K0 wiring harness now and make changes later, or am I better off buying a newer style harness now?
     
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  3. theraymondguy

    theraymondguy Well-Known Member

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    Swapping in a China engine will mean adding a CDI harness to your existing chassis harness. You'll also have to decide if you want to go 12V battery, lighting, horn, and regulator/rectifier or retain 6 lighting, battery, horn, and just update your regulator/rectifier. http://dratv.com/ctsubcdiwiha.html

    12V is the way to go for superior electrical performance (especially lighting), but there is a substantial investment to be made in time and funds.

    Retaining 6V will be much easier, cheaper and have you topping up the headlamp fluid before each trip http://www.absoluteastronomy.com/topics/Headlamp. Adding substantial engine power makes 6V lighting even more fun the first time you realize you can actually cover more ground than the headlight can illuminate - literally traveling faster than the speed of light :13:.

    Either way if your original chassis harness is poor, a new one is an inexpensive and important upgrade. I understand new OEM harnesses are no longer available... CT70KO CT70HK0 MAIN WIRE HARNESS 400085 (205N)
     
    #2 theraymondguy, Jan 21, 2012
    Last edited: Jan 21, 2012
  4. racerx

    racerx Administrator
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    I like that, it dovetails nicely with my time machine view of these little bikes... I'm saving that for another thread. The more cynical might be happier with the term "faster than the LENGTH of light":21:

    Technically, total wattage is what matters; volts x amps = watts. In the real world, circa 2012, 12v electrical components (including bulbs) are far more plentiful...making life a lot easier for those looking for improved lighting - just as TRG sez - unless you're an electrical wizard on a mission.

    A K0 electrical system is about as basic as it gets, including parts availability and 12v/CDI conversion. Typically, the lighting circuit uses existing harness leads, with minor mods like a modular plug at the reg/rec end. CDI wiring, for the most part, is self-contained except for the kill switch lead. As long as you have wiring schematics and a stub harness for the CDI plus some very basic electrical understanding, it's an afternoon's project.

    There's nothing wrong with a repop harness, excellent value for the money. Just unwrap the spliced connections and solder them - voila! good-to-go. Won't even upset the purists...much:3:
     
  5. Waveraider

    Waveraider Member

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    Thanks guys. My wiring harness is FUBAR, and I had planned on replacing it anyway. So it sounds like I just get the K0 Harness from dratv. Also, like it might be a good idea to convert to 12v now, instead of later. Any thoughts?
     
    #4 Waveraider, Jan 21, 2012
    Last edited: Jan 21, 2012
  6. theraymondguy

    theraymondguy Well-Known Member

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    12V 10W bulb to 6V 10W bulb the difference will be so marginal you'd need at least a good to high quality DMM to note the difference if not an oscilloscope. Under demand, a rated wattage 12VDC charging system will hands down out perform an equally rated wattage 6 VDC system due to losses; from hysteresis losses to heat saturation to plain voltage drop across resistive connections the difference can be day and night, especially with an inductive load like lighting.

    I tend to continuously focus on lighting; please understand the reason is that the lighting circuit is the most demanding.

    Don't bother with converting until you've actually made the engine swap. If your harness is really ratty and your battery tired, simply upgrading the harness alone will make a nice difference to electrical performance. Good clean grounds, a dab of di-electric grease on every connection you make or can disassemble and you're on your way.
     
  7. racerx

    racerx Administrator
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    X2 on theraymondguy's advice, top-to-bottom.

    I've never been completely satisfied with CT70 lighting, either...so the pursuit of better has been ongoing & will continue, probably until someone finds a way to achieve headlight output equivalent to a 65W H4 bulb. I'm not holding my breath for that one...:4:
     

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