Need help with magneto coil

Discussion in '2-Stroke Engines' started by jeffro81, Sep 15, 2009.

  1. jeffro81

    jeffro81 New Member

    Hi i was wondering if anyone can tell me about the magneto coil,ive got a new jap 80cc motor and it would'nt start,it had no spark so i checked the cdi on a mates bike and that works fine,so we looked at the magneto coil and found that it needed adjusting badly,and HORRAY it worked great,the next day i went to go for a decent ride to start to run it in and it wouldn't go??checked for spark and no spark again so i adjusted the magneto again and checked the cdi,cdi works on mates bike but still no spark,could this just be my magneto coil??any ideas would help heaps,thanks

  2. GearNut

    GearNut Active Member

    The most common problem is poor wire connections between the magneto and the CDI box. Every once in a while the kill buton in the throttle grip buggers up too.
    They are worth a look in.
  3. jeffro81

    jeffro81 New Member

    Thanks for the advice gearnut,i disconnected the kill button and cut the connectors off and reconnected the wires straight to each other and still no go, do you think its proberbly the magneto,im thinking it most likley is:-(thanks
  4. GearNut

    GearNut Active Member

  5. MikeJ

    MikeJ Member

    Disregard.... I see you did this.For what it is worth, I did not trust those press-together brass fittings from the magneto. I cut them off and soldered respective wires together for a good connector. For best connection, use solder flux.
  6. Al.Fisherman

    Al.Fisherman Active Member

    Attached Files:

    Last edited: Sep 16, 2009
  7. sparky

    sparky Active Member

    Hey Al...

    How did you connect the "connector" to the wire? Solder?
  8. jblokker

    jblokker New Member

    photo (5).jpg

    does this look okay?

    -went up a hill with a mate, noticed it wasnt running to well. went to go back down and it made an pop and stalled, zero spark ever since.

    -new cdi and spark plug and still no spark

    - SkyHawk R80 from MBB Imports
  9. crassius

    crassius Well-Known Member

    get a meter and check the blue wire to ground for 320-370ohms (usually 2k scale is good for testing)

    if not, then check blue wire to the copper wires soldered at the top of coil (maybe the solder came loose)

    if it reads OK there, re-solder it - if not, a new coil is needed
  10. jaguar

    jaguar Well-Known Member

    all it can be now is the stator coil, unless you have a kill switch installed. In that case just remove it and test again.
  11. HeadSmess

    HeadSmess Well-Known Member

    didnt mention what you have the white wire connected to. cut it off at the coil!

    top left hand corner, that blob of solder. theres a wire coming from coil and soldered to iron core here. check it hasnt burnt out. if it has, get a new coil. (amendment...see bottom)

    if it hasnt, do the multimeter test. between that solder blob (or anywhere that should be "earth" and the blue wire...did someone already say it? 300 or so ohms.

    black to earth should be about 0.00000001 ohm(yes, your multimeter will just say 0 or 1 ohm :jester:)

    earth to white is about 6 i think?

    white to blue will be black to blue minus the black to white result...

    amendment! just thinking. i havent tried this yet, but...

    if the white to blue reading is around the 300 mark...that part of the coil is good. if you get open circuit between blue and black, or white and black at the same time...try the white wire and call it black. worth a shot :) the coils wound in such a way that it should work. as long as theres no earth connection via black at the time!

    edit..i do recall once, when i had a failure, and still used the white as a kill... i got home by holding the killswitch ON. and that was definitely a burnt out "earth" join when i checked the magneto.

    those lil terminal/plug fittings that fisherman showed...theyre whats in almost every brushcutter boot. feed wire through boot, poke sharp end of spring through ignition cable, pull boot back over. if you ever try salvaging one, youll know that they STICK ON!

    then look for "aero" grade plugs with the solid tops, not screw ons...