CDI question

Discussion in 'Lighting and Electrical' started by Scott.D.Lang, Jun 28, 2013.

  1. Scott.D.Lang

    Scott.D.Lang Member

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    our kit cdi's are junk so what is to stop us from useing a 6v coil from something else a MC or even a car? it may be a stupid question but if other cdi's are better why not use them?
     
  2. JustAnotherBozoOnABike

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    ...i'm still a noob myself bro but the way i understand it is that the stock CDI's are fine so long as you replace the plug wire and boot which is crap and should be replaced with an auto grade plug wire, ...and not a 'resistance' core plug wire, a 'wire' core plug wire is what you want.

    ...but like i said, i'm still a noob myself and my stock CDI is working just fine with the new wire and plug.

    peace, bozo
     
  3. 2door

    2door Moderator
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    The CDI is more than just a coil. It determines when the plug fires. Simply replacing the CDI with a standard ignition coil just won't work.

    It is also a myth that the kit CDI is unreliable and trouble prone. They perform well and will produce sufficient current to fire the plug for thousands of miles. If they were as bad as some people try to make them sound you'll have to ask yourself why most race bike builders rely on them instead of some of the overpriced placebos available.

    I also concur that you need to replace the kit spark plug and boot, especially the boot, to assure good performance from your ignition system. The kit plug wire is in fact superior to some of the resistance wire you'll get from auto parts stores. At least it is a metallic core wire which is lower in resistance than the parts store version. The biggest problem with the kit wire is that it is usually too short to allow mounting the CDI anywhere but close to the plug, usually on the bike's downtube. The insulation isn't the best quality either and is prone to cracking prematurely.

    Tom
     
  4. xseler

    xseler Well-Known Member

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    I also use the stock CDI with an upgraded plug wire.....works great!!

    The difference between a Rolex and Timex is $$$, but they both give the very same info.
     
  5. Huffydavidson

    Huffydavidson STREETRACER/MANUFACTURER

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    A CDI from a scooter with a coil as well . RCMachine (Freds Head) has a head with dual spark plugs and the last time I saw one on e-bay he had suggested using one of those little orange CDI box is with two coils to power both spark plugs. It was on like the second picture . Or build modified CDI , or buy a Jaguar cdi&coil.
     
  6. Scott.D.Lang

    Scott.D.Lang Member

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    thanks both of you. and Tom I was thinking that the cdi was much more then just a coil just was not sure. the reason I asked this question is either my stader in my new engine is bad or for some reason my cdi went out. tomorrow Im going to take the cdi off my sons bike and see if it will run then if not Im going to take the stader out of my old f50 and put in the f80 Im hopeing that I just had a weak stador and it went bad since I have one to replace it lol.
     
  7. Huffydavidson

    Huffydavidson STREETRACER/MANUFACTURER

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    Scott, I hope you know there's a way to meter that out and check it and see what's wrong .
     
  8. 2door

    2door Moderator
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    Scott,
    There has been a lot of discussion about the potential for damaging the CDI by spinning the engine without a spark plug attached and grounded. The general consensus is that it is very possible. This is probably why so many CDI failures are reported and my belief is that the kit spark plug boot is the culprit. They are notorious for falling off, breaking or not making a good electrical contact at the plug. If the boot is failing to provide that connection then it is very possible for the CDI to be damaged by the induced current that will take the path of least resistance and potentially ground to a component inside the CDI and therefore causing it to fail.

    The kit spark plug boot should never be installed and should go in the trash along with the kit instructions when the buyer first opens the kit box.

    Tom
     
  9. Huffydavidson

    Huffydavidson STREETRACER/MANUFACTURER

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    So, true Tom.
     
  10. Scott.D.Lang

    Scott.D.Lang Member

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    oh and tom I do belive that the stock wires are junk as everyone sez not doughting that at all just to cheap to replace things if it will work for a time
     
  11. Scott.D.Lang

    Scott.D.Lang Member

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    huffy I do but dont have a multimeter to test it.

    lol Tom well I am useing the stock wire and boot but I did inspect it closely when I did my build same with my sons and to tell the truth they both looked better then some wires Ive used on cars lol. Im leaning towords the stador because it never had any cdi problems with the old motor and somewhere Ive read that from time to time the stators are bad out of the box.

    it just would of been nice if there was a cdi that we could go to a auto parts store to get. as far as the jag cdi if its built right I dont see it being a gimic but when I built turbo cars the one upgrade I did no mater what was a accel or msd coil and it always made a noticeable diffrence.
     
  12. 48ccbiker

    48ccbiker New Member

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    A high voltage coil is essentially two coils, both sharing the same ground. With no path for the spark (when cap isnt on plug) then the voltage can be excessively high and spark across coils, going back to the CDI and damaging it.
    Although the Jaguar CDI is not really essential for most people I do think it can always lessen high rpm vibration which is a major point of dissatisfaction with the China Gas engines. There may be other CDIs that work on it also.
     
  13. Huffydavidson

    Huffydavidson STREETRACER/MANUFACTURER

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    Scott, they give them away @ HF. If you don't have the coupon its like $5
     
  14. Scott.D.Lang

    Scott.D.Lang Member

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    yea but got to make that 20mi round trip there and back lol hard to do with out my bike lol
     
  15. Scott.D.Lang

    Scott.D.Lang Member

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    that said it is now on my list of things next time I go to HF
     
  16. crassius

    crassius Well-Known Member

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    while there, don't forget it needs a battery
     
  17. Huffydavidson

    Huffydavidson STREETRACER/MANUFACTURER

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    Harbor Freight multimeters, flashlights, headlights and taillights all come with batteries .Imagine that !! LMAOlaff
     
  18. bigbutterbean

    bigbutterbean New Member

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    Yep, got me a $3 multimeter at hf a couple months ago. Came with a battery. I only use it to test my batteries when my lights aren't working (7.2v nicads that power my headlight and brake light), but so far it works fine. Also bought other tools there with coupons, and no problems so far with any of them.
     

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