AC-CDI v2.7

ACCDI v2.7+ for 50cc to 800cc engines

What is better on ACCDI v27+ ?

Easier No jumper to cut or to sold. Every function has its own DIP Switch.
Universal More DIP Switches to adapt to different engines.
Safe 2 types of input to stop the ignition: Ground to Kill and Power to kill.
Powerful 50% more energy for bigger engine from 350 to 1000cc with a 1.5uf 400volts capacitor.
Reliable High quality trimmer. (European Piher brand)

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. (Lighting coil)
– HV (High Voltage around 100Vac) to charge the ACCDI. (Charging coil)
This AC-CDI only uses 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.


PICKUP

– This CDI works with 1 pickup and 1 reluctor (the metal strip on the flywheel) [A,B].
– This CDI works with 2 pickup and 2 bars [E,F].
– This CDI DOES NOT work with 1 pickup and multi-pulses pickup (ie 2 reluctors on flywheel) [C,D].
– This CDI DOES NOT work with 1 pickup and missing tooth flywheel [G].

– When the engine has only ONE pickup, the 2 wires are connected to HI and GND inputs.
– When the engine has TWO pickups (for Low speed and High speed), the 3 wires are connected to HI, LO and GND inputs.

Pickup Polarity

Be careful: If the wires are swapped then the pickup polarity will CHANGE !

A genuine Yamaha pickup is often Positive first then Negative (PN) but if you swap the 2 wires of the pickup, the polarity will be Negative then Positive (NP) therefore the DIP switches setting for PN will NOT work anymore of course !
Solution: Rectify the pickup connection or use the settings for NP engines.


Does it work on my bike?

List of bikes with 1 pickup this CDI works on.
List of bikes with 2 pickups this CDI works on.


 

DIP SWITCHES


SW13 setting


SW13 setting.
.
Click here for more info

HOW TO SET DIP SWITCHES?

You have to know if the bike has 1 or 2 pickups.
And for each pickup what is the polarity: PN (Positive then Negative) or NP (Negative then Positive).

Connect a scope between Ground and pickup wire to check the polarity.
If you don’t have a scope at hand, you can see the polarity with an old voltmeter.
(See video ).

If you still don’t know you will have to test every possibilities… Follow those guides:
Tests all settings for 1 pickup.         Tests all settings for 2 pickups.


SW14 setting


 

2 STROKES

SW14-1, SW14-2: Advance timing
On 2 strokes engines it’s necessary to lower the timing at HIGH RPM.
4 strokes engines: set Switches N°1 and 2 of SW14 to OFF (default).
2 strokes with Small reduction of timing : set Switch N°1 of SW14 to ON.
2 strokes with Medium reduction of timing : set Switch N°2 of SW14 to ON.
2 strokes with Large reduction of timing : set Switches N°1 and 2 of SW14 to ON.


KTM

SW14-3, SW14-4 : KTM setting
All engines, set Switches N°3 and 4 of SW14 to ON (default).
KTM engine, set Switches N°3 and 4 of SW14 to OFF.


SENSITIVITY

SW14-5: pickup Sensitivity
Pickup that puts out 2 to 30volts, set Switch N°5 of SW14 to ON (default).
Pickup that puts out 30 to 150volts, set Switch N°5 of SW14 to OFF.


SW14-6: Not used
Can be on or off.


INPUT OUTPUT

KILL

A Kill switch input is available “K“.
Ignition stop if connected to GROUND.


SAFETY

A Safety switch input “S” is available (for Side stand, Clutch, Neutral, Main switches…)
Ignition stop if connected to +2v to +12Vdc.


CHARGING COIL

– If the charging coil is internally grounded, then connect the only wire to “ALT” input and leave “ALTg” not connected. Note that DIP SW13-6 will have to effect.
– If the charging coil is NOT internally grounded, then connect the 2 wires to “ALT” and “ALTg” inputs; Order has no importance.

SW13-6 DIP ON: Less voltage.
SW13-6 DIP OFF: More voltage (default).


LED

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


TACHOMETER

A tacho output “TAC” is available. The output voltage is +12v (even if no battery or 6v battery)
Notice that it’s not a pure square signal.
Connect a tachometer that does NOT need a 50% square signal (50% off, 50% on)


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?

  • TROUBLESHOOTING

    Click here for more info
     
    You will need a DC voltmeter. The best is an old “Analog Needle meter”.
     

    Step 1

    Download 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 the metal part 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 SW13-6 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 then quickly decrease.
    (Due to the capacitor discharging into the CDI and the voltmeter).
    If not: Check grounds, connections, joints, charging coil (stator), change switch 6 position.

    Step 2

    Download troubleshoot step2
    – Don’t connect any pickup.
    – Don’t connect the Kill Switch.
    – Turn SW13 DIP Switches positions 1, 3, 5 to ON.
    – Turn RV1 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 in the same second:
    – Connect a 12v battery between GND plug (ground) and HI input:
    – Labeled “P” Led turns on.
    – The big 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

    Download troubleshoot step3
    – Don’t connect the Kill Switch.
    – Turn SW13 DIP Switches positions 2, 3, 4, 5 to ON.
    – Turn RV1 to the minimum resistance (Position: 0).
    – Connect the pickup coil between a GOOD metal frame (ground) and HI input of the CDI.
    – Kick start or electric start to load the capacitor and send trigger pulses:
    – The main capacitor C1 is charged and the voltmeter should read 100 to 200Vdc.
    – At the same time, when the piston approaches the TDC and passes in front of the pickup, a pulse is created by the pickup:
    LED blinks. (P or N or both leds according to the type of pickup)
    – The pickup pulse then trigger the SCR and the big capacitor C1 discharges into the ignition coil, a
    spark must fire at the sparkplug.
    If not: Check grounds, connections, joints, pickup coil, RV1 is set at 0, reverse the 2 wires of the pickup coil.


    VIDEOS.

    Click here for more
     
    Pickup polarity (PN or NP):


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