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Thread: Coil dying?

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  1. #1
    Atomic City Boxer 154048's Avatar
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    Coil dying?

    Hello all,

    When a coil fails, does it die immediately? Or does it show 'symptoms' for a while? I am still trying to fine the source of my electrical gremlin (1980 R100 point system; two coil). I have a very sporadic issue where, at highway speed, the GEN light suddenly comes on brightly; the tach goes crazy and the engine begins to run very roughly...Then the light goes off and everything is fine.6

    I have cleaned connections, found no damaged wiring, put on a new condenser and voltage regulator. It doesn't seem to be a charging issue...more like I lose energy to the ignition system,..and it is so unpredictable. Sometimes after a few minutes riding..other times after hours...or not at all?

    I am flummoxed....
    Steve in Santa Fe
    1980 R100RT
    2005 DR 650

  2. #2
    Administrator 20774's Avatar
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    Seems to me that a basic problem would be grounds. You can loose the charging system and end up just running on the battery. If the ground for the battery were to be flaky, your ignition could falter. Be sure all of your grounds are fine. You could have a pinched wire somewhere or something around the coils is touching the tank in certain situations.

    Have you cleaned the tower connections where the spark plug wires insert? Have you measured the resistance from one spark plug cap to the other? Should be 20-22K ohms. That will be a static reading, but something to check.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  3. #3
    Alps Adventurer GlobalRider's Avatar
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    Faulty ignition switch?

  4. #4
    Atomic City Boxer 154048's Avatar
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    I had considered the ignition switch, so took it out and cleaned the connections...While riding I wiggled it alot, but nothing seemed to happen.

    Kurt, your suggestion about if the engine is just running on battery for a short time, the ignition could falter makes good sense. I'll get out tomorrow and look to see how groundings look.

    Thanks!
    Steve in Santa Fe
    1980 R100RT
    2005 DR 650

  5. #5
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    Possibly an intermittent fault in the kill switch

    Adam

  6. #6
    Atomic City Boxer 154048's Avatar
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    The kill switch is next on my 'contacts needing cleaning' list. At least, when I get this figured out, I'll know that my wiring system is clean and tight.

    Last week I thought I had found the issue...I saw that my electric tach would go crazy at the same time the GEN light would flash...Then, the tach stuck at 3000 RPM and wouldn't budge. When I turned the ignition off, it went back to zero...but then the next time I rode it went to 2500 and stuck again...So I unhooked the tach from the coil, and all seemed well...until about an hour of riding, and I had another 'episode'...So strange...
    Steve in Santa Fe
    1980 R100RT
    2005 DR 650

  7. #7
    Registered User dmftoy1's Avatar
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    Don't know if this is of any help to you or not but I spent all day yesterday chasing a gremlin that I thought was the ignition switch but turned out to be the starter relay.

    The hot red wire that feeds the ignition (terminal 30 on my bike) appeared to have voltage off/on but was acting strange. I finally started using a test light instead of a multimeter and noticed that even thought I had 13+ volts at the switch there wasn't enough juice to light the test light. Working backwards I found that the internal jumper in the starter relay was bad.

    I'm not saying this is your problem but the failure mode could potentially cause the problems you describe. (Mine "failed" when inducing a hirer load across the wire by flicking on the high beams.

    Good luck!

  8. #8
    Atomic City Boxer 154048's Avatar
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    Starter relay...Now That is an interesting thought....and the test light idea is sound...Thanks!
    Steve in Santa Fe
    1980 R100RT
    2005 DR 650

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