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    • #3749
      • Topics: 1
      • Replies: 0

      Hey guys i have a gt125r that I have purchased I got all the electrics but no spark I have a feeling it’s the wrong CDI unit the part number is 32900 h M815.. the rest I can’t make out. The previous owner mentioned about putting a 250 ecu to increase acceleration and give it more revs. To be honest I’m not too knowledgeable with bikes. Was hoping for some advice nor ideas on what it could be

    • #3756
      ♠️ MARCEL
      • Topics: 45
      • Replies: 1,892
      North UK

      [moved to technical]


      M815 GT250  | M815 GT125 | M795 GT125 are fine to use.  The 125cc engine doesn’t care which one is used as they do the same job.

      If you take out the spark plug and place it on the frame or engine bolt, and no spark is visible, then attack the following:

      • SideStand Switch  (Cut & bin it) – Then bypass it (wires joined) & tape it hard from water invasion.
      • Clutch Switch  (at the hand lever) – I wouldn’t bypass it, but it can cut sparks even while its running. A multi meter will say 0 ohms if its dead (whenever you press it or let go)
      • Neutral Switch is lit up on dash ? – The plug is above the sprocket cover near the shock.
      • Go to your Magneto/Stator => Find its blue/green plug => probe the pins with the multi meter => it should say around 80-100 ohms healthy. Bike won’t start without this thing.

      Second stage, involves your ignition coils  (common failing units as they are cheap built)

      • Unscrew anti clockwise the “BLACK PLUG CAP” away from the HT LEAD
        Put a meter inside both ends,  tell us how many ohms it says under 20,000
        (20,000 or  20K on your meter display)
        Do this for front and rear.
      • Since the “COIL” on the frame now has an exposed “HT WIRE” … => Put one wire of meter there (red)   and  also (black wire of meter) on the FRAME (unPainted surface or bolt)
        It must be under 6,000 ohms healthy   (or 6K on your meter)

      Last thing, it’s still the coils… We are checking the “terminal pin” next.

      • Switch the meter to under 200 ohms (the lowest figure on meter)
        -> Red meter on the “TERMINAL PIN” of coil
        -> Black meter probe on the “frame” (ground)
        ==> Let us know what it says ?

      Let’s do these before we dive deeper in to the bike,  hopefully not though! – You can copy this reply and re-write it with your answers in numbers , so its easier to see each device i mentioned is in spec according to the books.

      Good luck

      // Meditation doesn't mean you have to sit still....

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