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Discussion Coil on plug conversions

Discussion in 'Tech Tips' started by Linkin, Aug 24, 2017.

  1. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    I figure there is enough interest on this topic to have a dedicated thread for it.

    Some good links to read:

    http://www.v4spark.com/V4-COP.htm

    http://www.sportdevices.com/ignition/ignition.htm

    http://www.dtec.net.au/Ignition Coil Dwell Calibration.htm

    https://spdispark.com/pages/frequently-asked-questions-dwell.html

    http://www.jetav8r.com/Vision/IgnitionFAQ.html

    There are a few reasons why you would want to do this mod. You will be replacing your old coils with newer ones (they can and do go faulty, as well as degrade with age). You eliminate the spark plug caps and high tension leads as failure points. If you have a coil on plug unit fail they are easier to replace, as you only need access to the plugs, whereas the old coils are usually bolted to the frame somewhere. Generally the new coils are lighter, so you save a small amount of weight as well.

    If you run an aftermarket programmable ignition unit, you open up options for using direct fire instead of wasted spark, as well as programming dwell time and ignition advance.

    For the record, our 4cyl 250cc grey import shiteboxes use TCI - Transistorised Coil Ignition and not CDI - Capacitor Discharge Ignition. What's the difference? Look in the links above.

    When selecting which coils to use, there are a few things to consider:

    Resistance of the standard coils vs. coil on plug units is the main concern. For example on the ZXR250C, one coil (firing two plugs) has a resistance range of 2.3-3.5 ohms on the primary side. Therefore, the primary resistance of the coil on plug unit (firing one plug) must be half of this, so 1.15-1.75 ohms is the range you would need.

    If you use coils with too low a resistance, you stand at risk of overheating the bike's standard wiring, damaging the coils, and damaging the TCI unit. You will not gain anything by running low impedance coils.

    You also have to consider the physical dimensions of the new coils. They have to be the right height, and the seal up near the connector has to match the diamater of the of the old spark plug cap. On bikes with exposed plugs like the FZR250, you don't have to worry about this.

    OK, so you've selected some coils and now you need to wire them up. How do you do that? With a standard TCI unit, it has to be done so to work with wasted spark. @my67xr made a nice picture so I will use it:

    [​IMG]


    The only thing I would change here is leaving some wire untaped from the connectors, so if you go for a dyno run it makes it easier to get the engine RPM signal off the spark lead.

    Will get some pictures of my conversion with the ZXR as it takes place in the next few weeks.
     
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    Last edited: Aug 24, 2017
  2. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    Here's a better picture

    pencil coil.jpg


    If you want to use some expanding sleeve to cover your wiring, Jaycar sell it cheap
    The woven design is good for letting out heat as well
    To expand it, just push the sleeve together and it expand's, then let go and it'll go back to it's original size
    You can put 20mm or so of Heat shrink over the end's to make it look tidy, and it come's in a few different colour's too

    3mm Expandable PPS sleeve (heat resistant) 2 metre length $2.50

    6mm Expandable PPS sleeve (heat resistant) 2 metre length, $3.25
    10mm Expandable PPS sleeve (heat resistant) 2 metre length , $5.95

    braided-heatshrink-sleeve-10mm-x-1-2mImageMain-515.jpg

    There is also the new PVC wiring tubing that Litetek sell's now too

    PVC_Tubing_Image_02.jpg





    You could make 2x seperate loom's for the coil's, that might make thing's easier to work out which plug is for 1 and 4 or 2 and 3 etc
    And then just connect it up to the factory harness as they usually have a plug for each of the original dual fire coil's.

    And waterproof 2 way plug's and socket's are cheap on ebay too
    http://www.ebay.com.au/itm/10x-2-Pi...363241&hash=item48a0be02e4:g:YOMAAOSwZs1ZiW4K

    s-l225.jpg



    I will see if i can find the spec's for the coil's (length and ohm's) and list them up here with some of the bike's they came off
     
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    Last edited: Apr 16, 2018
  3. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    This may need to be updated/edited later when i find out more detail's of the spec's ?

    Denso coil's


    129700-3630, 1.3 Ohm's primary, xxxx K Ohm's secondary, length xxxx
    Used on 1999-2003 ZX9,


    129700-3881, 2.5-3.1 Ohm primary, 11.8K to 15 K Ohm secondary, length xxxx
    Used on xxxx


    129700-4150, 1.3 Ohm's primary, xxxx K Ohm's secondary, length xxxx
    Used on xxxx

    129700-4400, 1.5 Ohm's primary, xxxx K Ohm's secondary, Length 127.7mm (5")
    Used on 2001-2003 GSXR600, GSXR750 2001-2008, and 2001-2007 GSXR1000


    129700-4580, 1.5 Ohm's primary, 10.8K -16,2K Ohm's secondary, Length xxxx
    Used on 2003-2007 Z1000, 2006-2020 ER6N, 2007-2008 ZR750, and 2005-2006 Z750,


    129700-4800, 1.6 Ohms primary, xxxx K Ohm's secondary, Length 139.7mm (5.5")
    Used on some 06-07 Suzuki GSXR600 GSXR750

    129700-5150,


    129700-5350, 1.1 Ohm's to 1.5 Ohm's primary, 10.8K -16,2K Ohm's secondary,
    Used on 2006-2020 ER6N, 2007-2008 ZR7502010 Z750



    If needed you could alway's boost up the Ohm's a little by using a 25watt resistor with the corrected Ohm's, eg add .6 Ohm's or 1.5 Ohm's etc to equal the factory spec's of your coil's.
    These resistor's can get expensive though

    s-l225.jpg
     
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    Last edited: Aug 25, 2017
  4. kiffsta

    kiffsta Administrator Staff Member Dirty Wheel Club Contributing Member

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    I have a set off an 01 zx6 and some off a 02 gsxr600 if anyone wants to do this conversion

    IMG_1577.PNG
     
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  5. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    After playing around with the 12790-4840 coils I found they are twice as long as the need to be.

    9AQlH0i.jpg

    For a good fit on the ZXR250, the length from the tip of the coil to the first edge of the oil seal needs to be 2 inches. Then the oil/dust seal will work and you won't foul against anything.
     
  6. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    Do you have a pic of the coil next to a stock plug cap ?
    Maybe a pic with a spark plug fitted to each too?
     
  7. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    I don't as of yet, but I will get some pics. I know what length coil I'm chasing now so will do a comparison.
     
  8. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    So you need some of the 129700-35** or 129700-36** coil's with the correct Ohm's ?
     
  9. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    Unsure. Just looking at ebay, Denso 129700-4740 should be a perfect fit.
     
  10. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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  11. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    Scratch those off the list then.

    Just checked the service manual for the Ninja 300 in the resources section, range for the primary winding on the coils is 1.1-1.5 ohms, they should be suitable if the length is OK. And they are cheap.
     
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  12. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    When I told the Ignitech people I might use COP on my Yamaha they said "Do not use coils from Yamaha R6 to 2005 year, GSXR750 1998-99 and GSXR600 1997-2000."
     
  13. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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  14. my67xr

    my67xr Well-Known Member Premium Member Contributing Member

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    $30 US each for inductive pencil coil plus post
     
  15. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    They might fit the bill perfectly. Good find.
     
  16. Spotthedogg

    Spotthedogg Active Member

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    I have CBR600RR coils on my VTR250 with a resistor but they are awful long, would consider replacing with some shorter ones for sure.


    Sent from my iPad using Tapatalk HD
     
  17. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    OK after firing off a message to an ebay seller with Ninja 300 coils, I got the measurement I've been chasing - the length from the tip of the coil (with the rubber end removed. The reason for this is because the rubber tip extends further down. The plastic end underneath stops on the flat edge of the metal tip of the spark plug) to the beginning of the seal near the connector. On the CBR1000RR coils, it is 3.4" but with the Ninja 300 coils it is 2.6" - so they are nearly a whole inch shorter.

    I'm hoping that the Ninja 300 coils will fit and clear the radiator shroud/fan without having to make modifications, and be less likely to vibrate loose.
     
  18. kiffsta

    kiffsta Administrator Staff Member Dirty Wheel Club Contributing Member

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    I picked up a ninja 300 for wrecking tonight if you need some coils
     
  19. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    Thanks kiffsta, the seller on ebay offered me a set of 4 for $70 posterd so I took them up on it. Next time :)
     
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  20. kiffsta

    kiffsta Administrator Staff Member Dirty Wheel Club Contributing Member

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    Set of 4 ... it's only a 2 pot :)
     

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