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No Spark in Loncin 125 Chinese Cross: Magnet, Module, Coil Replacement Advice Needed

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  • #1 17206333
    Xx-xX
    Level 7  
    Posts: 7
    Rate: 13
    After exchanging the damaged magnet and connecting as before, I still did not have a spark, so I replaced the module and the coil, but I still do not have a spark. Can anyone help me?
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  • Helpful post
    #2 17206364
    DriverMSG
    VIP Meritorious for electroda.pl  
    Posts: 44094
    Help: 3984
    Rate: 4836
    Does this scheme match your installation?
    No Spark in Loncin 125 Chinese Cross: Magnet, Module, Coil Replacement Advice Needed
  • #3 17206393
    Xx-xX
    Level 7  
    Posts: 7
    Rate: 13
    Exactly the same
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  • #4 17206402
    DriverMSG
    VIP Meritorious for electroda.pl  
    Posts: 44094
    Help: 3984
    Rate: 4836
    Check the voltage between the green and the red wire. It should be over 50V at start-up.
    Check or disconnect the Kill Switch. It can not short pins at start-up.
    Check if you receive impulses at the start of the blue wire.
  • #5 17206540
    Xx-xX
    Level 7  
    Posts: 7
    Rate: 13
    I do not have electricity on the blue from the pulse generator

    Added after 13 [minutes]:

    You could say how the electricity from the magnet is going in turn between these elements:
    Ignition switch
    Module
    Coil

    Added after 5 [minutes]:

    Well, but above all, I do not have anything on the blue from the magnet. What to do with this
  • #6 17206982
    DriverMSG
    VIP Meritorious for electroda.pl  
    Posts: 44094
    Help: 3984
    Rate: 4836
    There the meter will not show much, it is only a minimal impulse. Measure the resistance between blue and green from the pulser.
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  • #7 17207003
    Staszek49
    Level 35  
    Posts: 2421
    Help: 228
    Rate: 1138
    Check the pulse pulse generator, the resistivity is about 120 - 140 ohms. Do not expect high currents from the pulser, because (as the name suggests) it gives only an impulse at a particular moment, i.e. when the "hump" of the magnetic wheel is over the pulser. Pay attention to its distance from the magnetic wheel, because it can not rub, the recommended distance is approx. 0.3 mm.
  • #8 17207858
    Xx-xX
    Level 7  
    Posts: 7
    Rate: 13
    The fact that the magneto is slightly exaggerated may have meaning or rather not. Gives foto magnet
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    • No Spark in Loncin 125 Chinese Cross: Magnet, Module, Coil Replacement Advice Needed 20180506_171004.jpg (144.85 KB) You must be logged in to download this attachment.
  • #9 17208227
    Xx-xX
    Level 7  
    Posts: 7
    Rate: 13
    The resistance between blue and green is almost 160 Ohms
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  • #10 17208431
    dziechu
    Level 27  
    Posts: 1609
    Help: 27
    Rate: 69
    The pulse generator (green and blue) can be connected to the LED (red, has the lowest "ignition" voltage, approx. 1.5V). For ProgCDI, they give the voltage range from the 2-30V pulse, so it must flash. Flashes should be visible at the start-up. They can be very short and hard to see, so it's best to check in the evening how it will darken.
  • #11 17218733
    Xx-xX
    Level 7  
    Posts: 7
    Rate: 13
    I measured the probe and noticed that the spark is but very little current is lost behind the module because on this wire from the coil there is only a small impulse. What a fault
  • #12 18050128
    RadziXK
    Level 6  
    Posts: 5
    Rate: 7
    What was the reason? I guess I have the same problem. Only that I do not have electricity at all from the pulser (blue and green cable). Everything from the spark I changed, the cables are probably ok.
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Topic summary

✨ The discussion revolves around troubleshooting a Loncin 125 Chinese cross motorcycle that is experiencing a lack of spark despite replacing the magnet, module, and coil. Users suggest checking the voltage between the green and red wires, ensuring the kill switch is functioning properly, and verifying the pulse generator's output. The resistance between the blue and green wires from the pulser should be measured, with a typical range of 120-140 ohms. Additionally, the distance between the pulse generator and the magnetic wheel should be approximately 0.3 mm to ensure proper function. Some users report minimal current output from the module, indicating potential faults in the ignition system.
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FAQ

TL;DR: Expect >50 V between green and red at crank; "Check or disconnect the Kill Switch" to avoid shorts. This quick guide fixes no-spark on Loncin 125/Chinese CDI ignition by verifying stator, pulser, wiring, and CDI basics. [Elektroda, DriverMSG, post #17206402]

Why it matters: It prevents endless parts-swapping by confirming each ignition stage with simple measurements.

Quick Facts

What are the first checks when there’s no spark on a Loncin 125 or similar Chinese CDI?

Start with three quick checks. Measure between green and red wires while cranking; you should see over 50 V. Disconnect the Kill Switch to ensure it does not short the CDI during start. Check that the CDI sees trigger impulses on the blue wire. [Elektroda, DriverMSG, post #17206402]

How much resistance should the pickup/pulser have, and what gap is right?

Typical pulser resistance is about 120–140 Ω between blue and green. Set the air gap to roughly 0.3 mm so it does not rub. The pulser produces a brief trigger when the flywheel “hump” passes. “Do not expect high currents from the pulser.” [Elektroda, Staszek49, post #17207003]

Why does my multimeter show nothing on the blue pulser wire?

The pulser produces only a very short impulse, so many meters will not display it. As the expert noted, it is “only a minimal impulse.” Instead, measure the resistance between the blue and green pulser wires to confirm integrity. [Elektroda, DriverMSG, post #17206982]

How do I LED-test the pulser quickly?

Connect a red LED across the pulser’s blue and green wires. Crank the engine and watch for flashes. A red LED has a low turn-on voltage and will show the brief trigger. For ProgCDI systems, pulses fall in the ~2–30 V range. Test at dusk if flashes are faint. [Elektroda, dziechu, post #17208431]

What voltage should I see feeding the CDI while cranking?

Measure between the green and red wires during cranking. You should read over 50 V. Low or no voltage indicates a charging coil or wiring issue upstream of the CDI. Confirm connectors and grounds before assuming module failure. [Elektroda, DriverMSG, post #17206402]

Should I disconnect the Kill Switch during diagnosis?

Yes. The Kill Switch must not short CDI pins at start, or the ignition will be disabled. Unplug it and retest for spark and trigger signals. Reconnect only after you confirm normal readings with it isolated. [Elektroda, DriverMSG, post #17206402]

What air gap should I set between the pickup and flywheel?

Set the pickup-to-flywheel gap to about 0.3 mm. Ensure it does not touch. The trigger occurs when the flywheel’s “hump” passes the pickup, so correct spacing and alignment are critical. Recheck the mount after any flywheel work. [Elektroda, Staszek49, post #17207003]

Is ~160 Ω across the pulser out of spec?

Yes. Typical pulser resistivity is about 120–140 Ω between blue and green. A reading around 160 Ω indicates drift or a mismatched pickup. Re-verify the gap and consider replacing the sensor if spark remains absent. [Elektroda, Staszek49, post #17207003]

How can I confirm my CDI wiring is correct before testing parts?

Compare your harness to the reference diagram. Confirm wire colors and pin positions match the shared CDI layout. Fix any pin-out errors and poor connections first, as wiring faults mimic failed modules and coils. [Elektroda, DriverMSG, post #17206364]

I have no voltage from the pulser at all—what should I do?

Do not rely on live-voltage reading; the pulse is too brief. Instead, measure resistance between the blue and green pulser wires to verify the sensor. Replace the pickup if the reading is abnormal or unstable when moved. [Elektroda, DriverMSG, post #17206982]

Can a deformed or altered flywheel (“magneto”) stop the trigger?

Yes. The pickup fires only when the flywheel’s “hump” passes the sensor. If that feature is damaged or misaligned, the CDI will not receive a proper trigger. Verify flywheel condition and pickup alignment after any impact or service. [Elektroda, Staszek49, post #17207003]

Give me a 3-step quick test to isolate no-spark without swapping parts.

  1. Measure green-to-red while cranking; confirm >50 V.
  2. Disconnect the Kill Switch and retry for spark.
  3. Check for a trigger on the blue wire (or verify pulser resistance). If any step fails, repair that stage first. [Elektroda, DriverMSG, post #17206402]

I replaced the CDI and coil and still have no spark—what next?

Validate inputs before suspecting new parts. Confirm the charging voltage (>50 V) on green-to-red while cranking. Isolate the Kill Switch to prevent shorts. Check that the blue pulser lead generates a trigger at start. Only after these pass should you re-evaluate CDI and coil. [Elektroda, DriverMSG, post #17206402]

Did this thread confirm a final root cause?

No final fix was reported. A later poster asked what solved it, citing no pulser output. Follow the voltage, kill-switch, and pulser checks above to identify your own root cause reliably. [Elektroda, RadziXK, post #18050128]
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