AC-CDI v2.6

v2.6

Characteristics.

  • For ONE or TWO* cylinders
  • Highly adaptable.
  • Can handle different pickups coils (Yamaha,Honda,Suzuki,Kawasaki,Zongshen)
  • Use the first pulse of the pickup signal for HIGH RPM, maximum power.
  • Use the second pulse of the pickup signal for LOW RPM , idle and easy start.
  • Works with 1 or 2 pickups.
  • RPM when CDI jump from LOW to HIGH is adjustable.
  • 2 LED indicators.
  • YPVS output to drive an YPVS box.
  • Need a working charging coil for the capacitor. (or a DC converter)
  • Doesn’t need a battery
  • No rev-limiter (Tested at 20,000rpm)
  • 2 power available: for engines below or over 500cc
  • Running unit available in the shop ACCDI v2.6 or ACCDI v2.6+

Limitations.

This CDI only does the ignition task, it doesn’t use any safety like neutral and sidestand. Use only Kill Switch.

  • If any, connect Neutral switch wire to Neutral indicator.
  • If you need “Side-stand security” then connect the Sidestand switch to the KILL input on this CDI.
  • Only works with VR pickup (Variable Reluctance AKA pickup coils)
  • Cannot work with Hall sensors or points.

WIRING

  • How To wire this CDI?
  • How To hook this CDI on a Yamaha XT600
  • How To hook this CDI on a Yamaha XT550
  • How To wire this CDI to a 2 cyl 2 strokes?

  • Compatibility and DIP switch positions

    List of bikes this CDI works on.

    Not compatible bikes:
    Yamaha YT250 (1995-) because it use a TCI
    Yamaha XMax 250-500 scooter TCI
    Yamaha YZ400 (1978) MAGNETO
    Suzuki DRZ400 DCCDI
    Yamaha XT600E (1990-2003) [3TB/3UW/3UX/3UY/3WR/VJ01/DJ02/4PT] TCI
    Yamaha TT600 (1993-2005) [4LW/4GV/DJ01/5CH] DCCDI
    Suzuki Savage 650 TCI
    Yamaha SRX660 (1996) TCI


     

    DIP Switches function


    sw 1: ON= One pickup connected to HI input
    .... OFF= Two pickups connected to HI and LO inputs
    sw 2+5: ON= The first pulse of the pickup used for LOW rpm is Positive (PN)
    .... and the second pulse used for HIGH rpm is Negative
    sw 3+4: ON= The first pulse of the pickup used for LOW rpm is Negative (NP)
    .... and the second pulse used for HIGH rpm is Positive
    sw 4+5: ON= The first pulse of the pickup used for LOW rpm is Positive (PP)
    .... and the second pulse used for HIGH rpm is Positive
    sw 6: ON= Half Wave rectification: Normal spark. One side of the stator is connected to Ground.
    .... OFF= Full Wave rectification: Strongest spark. Stator is disconnected from Ground


     

    How does it works?

    On an ACCDI based engine, the charging coil (AKA stator) puts out:
    – LV (Low Voltage around 12Vac) for light and battery if any
    – HV (High Voltage around 100Vac) to charge the ACCDI.
    This AC-CDI only use the HV coil to charge the big C1 capacitor through a rectifier bridge.

    When the pickup is triggered, the CDI turns on a thyristor that discharge the capacitor inside the primary coil.
    This burst of energy into the primary induce a high voltage of few thousand volts into the secondary coil, enough voltage to create a spark at the sparkplug contacts.

    Here is a interesting video description of how a CDI works.


    Sensitivity
    This CDI needs a pickup that puts out 2 to 30volts.
    For pickup that puts out more then 30volts, cut the JP1 jumper to increase the range of RV1 trimmer.

    It doesn’t have seamless advance, it jump from LOW advance to HIGH advance.
    The moment when the CDI jump from Low to Full advance is adjustable by potentiometer RV2 (HI).

    Start tuning with RV2 at the maximum value 4 then slowly unscrew it to lower the resistance, therefore the RPM where it switch.


    Power
    This unit is available in 2 models:
    ACCDIv2.6 standard for engine from 50 to 500cc with a 1uf 250v capacitor
    and
    ACCDIv2.6+ with 50% more energy for bigger engine from 500 to 1000cc with a 1.5uf 400volts capacitor and a high quality trimmer (Piher brand)


    LED
    LEDs have “N” and “P” labels. They turn on when the CDI receive a Negative or Positive pulse on HI input.


    YPVS
    An YPVS output is available to drive a Yamaha Power Valve System control unit. (Y/G wire)
    (Cannot drive the step motors directly.)


    Math


    4 strokes 1 cyl= 0.5 * 1 = 0.5spark/rev (when no wasted spk)
    4 strokes 2 cyl= 0.5 * 2 = 1spark/rev
    4 strokes 4 cyl= 0.5 * 4 = 2sparks/rev
    2 strokes 1 cyl= 1 * 1 = 1spark/rev (= 4 stk 1 cyl with wasted spk)
    2 strokes 2 cyl= 1 * 2 = 2spark/rev


    TROUBLESHOOTING

    Click here for more info
     

    Step 1

    See: troubleshoot step1
    – Don’t connect any pickup
    – Don’t connect the Kill Switch
    – Connect the ignition coil to the COIL output of the CDI.
    – Remove the sparkplug from the engine and connect it to a GOOD metal frame (ground)
    – Connect the charging coil to the 2 ALT inputs of the CDI.
    – Connect a DC voltmeter between Ground and KILL pad.
    – DIP Switch N°6 can be ON for full rectification or OFF for half rectification.
    Other DIP switches positions don’t matter for step 1.
    Then:
    – Kick start or electric start a few times to load the capacitor.
    The voltmeter should raise up to 100 or 200Vdc.
    If not: Check grounds, connections, joints, charging coil (stator), change switch 6 position.

    Step 2

    See: troubleshoot step2
    – Don’t connect any pickup
    – Don’t connect the Kill Switch
    – Turn DIP Switches positions 1, 3, 5 to ON.
    – Turn RV2 to the minimum resistance (Position: 0)
    – Kick start or electric start a few times to load the capacitor.
    – Once the main capacitor C1 is charged and the voltmeter shows 100 to 200Vdc, then:
    – Connect a 12v battery between GND plug (ground) and HI input:
    Led turns on.
    – Capacitor discharge into the ignition coil and one spark must fire at the sparkplug.
    If not: Check grounds, connections, joints, SCR, ignition coil, spark plug cables, spark plug.

    Redo this Step 2 but this time connect the +12v battery to the LO input. (Led won’t light.)

    Step 3

    See: troubleshoot step3
    – Don’t connect the Kill Switch
    – Kick start or electric start a few times to preload the capacitor.
    – Once the main capacitor C1 is charged and the voltmeter shows 100 to 200Vdc, then:
    – Connect the pickup coil between GOOD metal frame (ground) and HI input of the CDI.
    – Kick start or electric start.
    When the piston approaches the TDC and pass in front of the pickup, a positive pulse is send by the pickup and trigger the SCR.
    LED blinks and the capacitor C1 discharges into the ignition coil and a spark must fire at the sparkplug.
    If not: Check grounds, connections, joints, pickup coil, RV1 and RV2 are at 0, reverse the 2 wires of the pickup coil.


    VIDEOS.

    Click here for more
     

    • Version 1.0:
    • Version 2.1:
    • Version 2.2:

    • Pickup polarity (PN or NP):

    • Marty bought a 1984 wrecked XT600 without ignition and harness wiring.
      Got it running again even if it seems like he has some carbs works to do…
    • Analog CDI v2.2 fitted a Scooter:
    • Analog CDI v2.4 on a DR125:
    • Analog CDI v2.4 on a XT125/1982:
    • Analog CDI v2.4 on a XT400:
    • Analog CDI v2.4 on a XT600:
    • Analog CDI v2.4 at 10,000rpm:

    • Analog CDI v2.4 at 15,000rpm:

    23 thoughts on “AC-CDI v2.6”

    1. hello Thierry, i have a yamaha xt250 2valves 1980, i run the bike with no battery, i just have front\rear lamps drived by the AC circuit (bike is heavy modified for enduro ).. does this CDI will work on my bike or it needs a battery\DC circuit?

      thanks

      paolo from italy

      1. If you had read this page you would know

        v2.6 Characteristics.

        For ONE or TWO* cylinders
        Highly adaptable.
        Can handle different pickups coils (Yamaha,Honda,Suzuki,Kawasaki,Zongshen)
        Use the first pulse of the pickup signal for HIGH RPM, maximum power.
        Use the second pulse of the pickup signal for LOW RPM , idle and easy start.
        Works with 1 or 2 pickups.
        RPM when CDI jump from LOW to HIGH is adjustable.
        2 LED indicators.
        YPVS output to drive an YPVS box.
        Need a working charging coil for the capacitor. (or a DC converter)
        Doesn’t need a battery
        No rev-limiter (Tested at 20,000rpm)
        Running unit available in the SHOP.

    2. thankyou, i was in doubt for this sentence:

      -Need a working charging coil for the capacitor. (or a DC converter)
      is the charging coil the one that drives the Dc converter and charges the battery?
      do i need a DC output to drive the ignition?

    3. Hi Thierry!

      I got now one V2.6, and I thinking about that may I should change the potmeters to these parts which are on the new picture . It’s matter something which part in it?

    4. Hi Thierry!

      On my V2.6 ACCDI the D9 “A7” type diode gone short to the ground at of this capacitor side, and it’s burnt out.
      Can you tell me what kind of diode can I repair with? And It’s possible to have other not visible damage in some of the other parts?

      1. Hi Takacs,
        Thanks for the feedback. The diode is a 1N4007 You can remove it and replace it by a short between Anode and Kathode.
        No other parts I can think of… It seems like high voltage jumps from diode to GND. I’ll increase isolation!
        What is the bike?

        1. Thank you for your answer!
          It’s an XT 550 from ’83.
          I thought only what if may the diode function is to protect the capacitor and then probably damaged that too.
          But then I will make a short there, thanks the help.

    5. Hi
      Great product! My XT600 lives again!
      I have a slight problem though as it won’t rev now past 3000.
      It looked like R3 burnt out.
      Any help would be appreciated

      1. Hi,
        Thanks, cool!
        Re R3 yes that can append sometimes and coming version will improve this point.
        R3 is rated for 150 and an overvoltage of 300v that can be reach sometime or if bad cnx with the sparkplug. (check this out)
        You can replace R3 (3k3) by 2 Through Hole 1k8 0.25 or 0.5w resistors in series between C2 leg and GND.

    6. I have a question for you about this unit! I am looking for an alternative for my 1995 & 1996 KX125. Would this work on my bike?? please let me know what the difference would be for a single cylinder 2 stroke!

    7. Sorry for the last question did not read everything that you have attached! I think this will work after reading everything. I am going to try it and see how it goes! Will respond on how things work for me and let you know what happens! 1996 KX125

      1. No problem. Do you have the wiring diagram of this model? I flipped though the www and saw there are some Kawa CDI WITHOUT external pickup!
        If yours is in this case there is a workaround to do, contact me in case…

    8. Hello
      I want to make CDI ignition system for an old bike.
      I need to know how advance curve can be adjusted. At startup mode advance should be 0 deg, max advance is 46 deg.
      Regards
      Ivan

        1. Thank you for your answer.
          Few more questions.
          1. Is Digital AC CDI can work with kick starting or need to be DC CDI?
          2. Is it important leght of the rotor signal protrusion – short or long?

          1. 1) what do you mean? DC CDI needs a battery.
            2) the question is: “Are the ignition settings important?
            This is ignition 101. No offense but if you want to create an ignition for an old bike you have to master differences between ACCDI, DCCDI, TCI, Magneto and DEEPLY understand how an ignition works !
            PS: and I cannot give private lesson 🙂

    9. Thierry,

      The AC-CDI v2.6 unit arrived! Wow, what a neat piece of hardware you have made here, Sir.

      I read the FAQ, but I still have a question, can you please tell me what the proper settings should be for the DIP switches? As shipped it arrived as:
      1: off
      2: off
      3: off
      4: on
      5: on
      6: off

      I checked your write-up here (https://transmic.net/2016/07/14/yamaha/) about Yamaha magnet signals, I was not sure if my switches are configured properly. Looking at the DIP settings above as it arrived in the mail today, can you tell me if I have these set up optimally for my 1982 Yamaha XT250? I appreciate any assistance that you can give to me!

      Thank you,

      Donovan

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