No Spark Even With new CDI- Help Please!!

Discussion in 'Motorized Bicycle Trouble Shooting' started by da1nonlysteven, Aug 6, 2011.

  1. da1nonlysteven

    da1nonlysteven New Member

    Dec 31, 2010
    Likes Received:
    Hello all!

    Was riding my bike the other day and it died slowly. After a bit of figuring I replaced the CDI ( used). It worked! Then about two weeks later and 150 kms of riding it died again very similar to how it did before. I did not notice going over bumps or anything when it died and the second time I heard a pop or bang, almost sounding like something had fallen off the bike.

    Once again troubleshooting I found that the coil was bad. ie. no spark coming from the plug.

    Ordered two new coils.

    Installed the new coil today and rolled it forward and got a tiny blue spark. Reassembled the bike, using the same method as before. Tried to go on a ride and no spark again. I know its getting gas & air from the carb for sure.

    Tried the other CDI and the exact same thing, so I would guess its not the CDI.

    I tested the leads coming from the magneto ( Blue and Black) and I am receiving between -2.5 to 2.5 volts so I would guess that it is operating normally.

    Any ideas or anyone else had this problem?

    Thanks in advance!

    Steven Gill
  2. rohmell

    rohmell Active Member

    Jun 2, 2010
    Likes Received:
    Remove the magneto and sandpaper the posts on which it sits in the engine. Also sandpaper the area around the magneto's bolt holes. You want to have a clean, shiny surface so that the magneto make good electrical contact with the engine.

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