ct70 engine wiring issues

Discussion in 'Tech Area' started by HomelessDave, Apr 5, 2019.

  1. HomelessDave

    HomelessDave New Member

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    about a month ago, i revived a 1980 CT70 that has been sitting since about 1985. It was running fine after i rebuilt the carb. After about 20 minutes the neutral light quit working, i think this was due to the bad battery (since replaced and it still doesnt work, it probably blew). the headlight and tail lights were missing already, so i cant give info on those. a few days ago, i was riding and it suddenly died, i was able to kick it a few times and it came back, but then died again. luckily i was only 3 block from home, i determined that it had lost spark. the cleaned the points and checked all the wiring and regained spark. yesterday it lost spark again, but i know that the yellow wire form the case is broken behind the fly wheel which will not come loose from the crank, i believed that it is seized to it ( i tried the flywheel tool). I dont know what that issue is, is that wire grounding? (think i would see it sparking or hear it). i am already considering swapping to a 125, but would like to get this running for another project first.
     
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  3. lukelaw1

    lukelaw1 Active Member

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    The yellow wire is from the lighting coil. I would pull the battery box and gas tank and check the wiring harness this is a typical home for mice.
     
  4. HomelessDave

    HomelessDave New Member

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    I have done this, there is no sign of mice ever living there.
     
  5. kirrbby

    kirrbby Well-Known Member

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    Sooner or later you're gonna need to get that flywheel off of there. I'd start putting a few drops of penetrant in there every day. Then try the puller again. When you get good torque on the puller, try whacking the end of the center screw with a hammer. Not too hard, but a good crack...to shock the rust bond, that has it froze up.

    Be sure to run the puller...the reverse threads...in as far as possible before you tighten the center screw.

    If ANY wire is grounding out under the flywheel, you won't have spark.

    BUT, the very most common reason for no spark is dirty old out of adjustment POINTS.

    Check clean repeat.
     
  6. kirrbby

    kirrbby Well-Known Member

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    Couple more stuffs...
    Your bike has a kill switch...they can malfunction...try unplugging it from the wire harness.

    The best way to start a stubborn CT70...put it in 2nd or 3rd...key on...run on...choke..? Then push it around in circles, down the street, etc. Get that motor spinning, sparking, and sucking air/fuel.
    Good luck.
     
  7. HomelessDave

    HomelessDave New Member

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    Thank you for your advice, but im not sure if the suggestion of the points is the issue. it had extreme blue spark (it would jump and inch no problem). I tried to push start it, we pushed it for 3 blocks and nothing. i think the issues are behind the flywheel...sigh...
     
  8. CT70Terry

    CT70Terry New Member

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    Is the battery still in the bike? Is the battery plug jumpered? Just a stab as you stated it was working and now it is not.
     
  9. HomelessDave

    HomelessDave New Member

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    Battery is in and charged. I have no working lights, but the horn has always worked and still does, plus a volt meter showed 6.3volts.
     

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