no spark

Discussion in 'Old's Cool' started by shawshank9110, Aug 2, 2014.

  1. shawshank9110

    shawshank9110 shawboy

    Joined:
    Aug 2, 2014
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    Ok. I bought a 77 triple. But has electronic ignition. I have replicated cdi, pickup coil, rectifier, and fuse box, and still no spark. Im going cross eyed looking at the wiring diagram chaseing wires because the guy I biught it from cut all wires that was once to the fuse box and direct wired them together. So mg question is, is there any stand alone ignition system to really clean up the bike and not have 10 miles of wire everywhere?
    #1
  2. Danjal

    Danjal Insert wit here.

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    Got points on that thing?
    #2
  3. concours

    concours WFO for 41 years

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    Hi, Welcome to the asylum. A triple WHAT did you buy? XS750 Yam? Trident? Sazook?
    http://www.boyerbransden.com/micromarkiii.html
    #3
  4. shawshank9110

    shawshank9110 shawboy

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    It is titled as a 77 Yamaha xs750 but has electronic ignition as the 78 came with. So im guessing it is a latter model of the 77. And no, there is no points on my old gal. Is there any simpler way to get my ignition to work without all the other wiring bs? Im trying to really clean the wiring up being it is a bobber project.
    #4
  5. shawshank9110

    shawshank9110 shawboy

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    Recent update. Got new rectifier. So I plug it in and keeps blowing main fuse. Ugh. Im running out of ideas here. Any ideas?
    #5
  6. concours

    concours WFO for 41 years

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    Tell us a bit about your skillset please... you have a DMM? Any experience with Ohm's law? Know how to measure resistance? This will help us know at what level to start.

    Trying to unravel a horrible amateur bodge job can be a bigger challenge than any other.
    #6
  7. ttpete

    ttpete Rectum Non Bustibus

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    Before you do ANYTHING, get your hands on a wiring schematic for that particular model. You'll be able to identify the wires by their color. Better yet, try to find a factory workshop manual. Google is your friend here. Chances are there will be a download. Look for forums that deal with vintage Yamahas.

    Wiring problems are something that can't be addressed online except in a very general way because nobody can visualize them.
    #7
  8. shawshank9110

    shawshank9110 shawboy

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    Thank you for your replys. Yes I have a dvom. I have grown up working on cars with my dad since I was a kid. So yes I am pretty knowledgeable. What im having problems with is trying to figure out what the guy did before me. The wiring harness has been chopped to crap. I have damn near memorized the wiring diagram for this model of bike. I am half tempted to find a new wiring harness that has not been hacked on and work from that. I mean the one on it is a rats nest. Good or bad idea?
    #8
  9. sailah

    sailah Lampin' it

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    For $50 it would be worth it to me to start with a better unknown (ebay harness) than your complete unknown which is just frustrating. Get the bike running THEN start slimming down the harness. You're just throwing random darts right now, get the darts on target and start focusing on your aim.

    Starting off with a complete rats nest is frustrating at best. I've done it. And I hear you about going blind on wiring diagrams. Do yourself a favor and get a decent harness that you are semi confident in. Start working down the line.

    My favorite first place to test is with the kill switch to run are you getting 12v at the coils. If not, it's a much more basic problem. If you are you can then focus upstream on trigger reg rec problems.
    #9
  10. MotorradMike

    MotorradMike MIL-TFD-41

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    I have a 1978 XS750 and a Haynes manual.
    If you need pics of something specific, let me know.

    Edit: The kill switch on mine was the cause of a very long intermittent engine quit scenario. Took a long time to find it.
    #10
  11. shawshank9110

    shawshank9110 shawboy

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    Thank you for the help. I may take you up on that. I just ordered a wiring harness today. Will keep everyone posted when I get it in and put on. Should be latter this week.
    #11
  12. Danjal

    Danjal Insert wit here.

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    PO hack jobs suck. Been through that before. Your best bet is the wiring harness as said,or repairing everything you touch back to stock.
    #12
  13. shawshank9110

    shawshank9110 shawboy

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    OK. Still no spark. Got a real nice harness and new kill switch. Still nothing. This thing is pissing me off. I'm about to sell the damn thing. Anybody have anymore ideas?
    #13
  14. MATTY

    MATTY BORDER RAIDER

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    Total shot in the dark here but is it the kill switch, there will be three wires in the kill switch two will be the coil feed that will suply coil. the other will be the starter solenoid wire.
    Get continuity to the coil, join the coil feed wire to the power in and the solenoid wire continued to the starter button, it should start.
    #14
  15. k-moe

    k-moe Long timer

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    Have you checked the coils for proper primary and secondary resistance?

    Have you checked the pickup coils for proper resistance?

    Do you have a known-good TCI to swap for testing? While TCIs are durable, the capacitors do fail eventually, and solder joints can fail.

    Have you checked the plug caps? They should be resistor caps, and the resistors can fail, or the retaining plug become loose.

    Have you removed the plug caps and cut back the plug wires to eliminate corrosion?

    Is the battery at full charge? Low voltage will spin the starter but not leave enough for the TCI.
    #15