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Spark plug wire resistance too high???

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  • Spark plug wire resistance too high???

    I have a DT90 i'm struggling with.
    It idles OK and runs Alright-ish on WOT. BUT: apart from that it's sluggish.
    Carb is thorouhgly cleaned. New plugs, checked gap. Fuel is good and fuel pump works nicely. Was going to measure coil resistance too, but couldn't find out how/where and flywheel is properly stuck..

    I checked the workshop manual, which says the wire caps should have ap**. 5k. ohm resistance, but all mine are around 10.k.ohm. Can this truly be the culprit?
    Here is a video of how it acts...

    Would like to just swap the caps, but they are practically IMPOSSIBLE to get a hold on here in Norway... Maybe there are some other caps that might fit?

    Any and all suggestions are very much welcome.

  • #2
    So. I also find it a little weird that Suzuki specifies max 5k ohm resistance on spark plug wire caps, but put on NGK TB10EM yellow 10k.ohm caps on their engines. I also have a DT75 with a perfectly good running motor, which has the same plugs, caps and values.

    Hopefully this mystery will come to an end before i give up...

    OK, so further testing has eliminated secondary Coils, Spark plugs and wires as the culprit.
    I suspect reed valves might need replacing, as well as believing one of the primary coils under the flywheel can be shot.

    The problem is, workshop manual and actual engine is not the same.
    On the engine i measured this.
    2021-09-13 16_40_18-Foto - Google Foto.jpg

    But according to wiring diagram and manual, there should be 6 wires in that plug: Black/Red, Green, White/Black, white/green, Red/white, Red/green. As you can see, I only have the ones underlined and red/black wire... WEIRD.

    White/black is measured to 220 ohm to ground
    Red/Black is measured to 220 ohm to ground
    Green and black/red is 220 ohm between them (Condenser charging coil)

    Black is negative

    Yellow/white is 170 ohm to ground
    Red and Yellow is 0 ohm to ground. (theese are as far as I believe the Battery charging coil and should be 0.4-0.06 ohm between them)
    2021-09-13 16_43_37-Suzuki Outboard Workshop Service Manual - All Motors by glsense - issuu.jpg
    2021-09-13 16_43_49-Suzuki Outboard Workshop Service Manual - All Motors by glsense - issuu.jpg
    Last edited by Steinrawr; 09-13-2021, 10:54 AM.


    • #3
      I got a tip to check the pulsing coils on the magneto, and one of them seems like it MIGHT be a little far away from the magneto, but I cant say for sure, and flywheel is SUPER stuck...
      This one is about twice the distance from the coil than the other. Gap should be 0.75mm. I would say gap here is around 1mm.

      2021-09-14 11_47_01-Foto - Google Foto.jpg

      So. The stuck flywheel.

      I dont have a puller tool with correct bolt threads, would I be able to pull ut off without damage to the teeth with this kind of puller?
      2021-09-14 11_49_16-Avtrekker -

      It's pracically impossible to get a hold on parts, so I cant risk braking anything.


      • #4
        This puller in pic is NOT a good puller for flywheel. The proper puller threads into flywheel (DO NOT THREAD too deep - only thread the thickness of the holes - damage will occur if the bolts go deeper). Loosen main flywheel nut till flush with shaft. Using the proper puller, thread the 3 bolts the thickness of threads. The large center bolt on puller pushes down on center of crankshaft. Leaving the nut flush on crankshaft prevents mushrooming of shaft. Once all bolts are properly in place, tighten center bolt. Once Center bolt is tight, strike center bolt head squarely with hammer. This should separate the crankshaft and flywheel (it should POP just to the flywheel nut).

        If you do not have the proper tools/ flywheel puller, do not attempt to remove flywheel. Take it to a good mechanic.

        Good luck, post back on what you find.


        • #5
          Another thought, if your Suzuki service manual is NOT for your specific motor, then everything could be skewed, wire colors, ohm readings, even which wires go to which coils?

          You must have the proper manual for this motor.

          Good luck, post back.