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Electrical gremlins

Discussion in 'Motorcycle Tech Talk' started by Red Rider, Jan 25, 2018.

  1. Red Rider

    Red Rider Well-Known Member

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    What went wrong is now right - I finally have my bike back from the shop and am pleased that I would have never been able to get it running right myself: the Dyno was key.

    As some my recall, I rode from here in Nevada to Texas & back in October and my bike has been in the shop ever since, until yesterday, because it was running like crap and hard to start - but not always. Turns out that it had multiple issues that weren't necessarily constant. The Twin-Tech ignition unit was "faulty", but in a way that even the Twin-Tech techs were unfamiliar with. They could not explain why it failed like it did, but once replaced it was obvious that it was one of the problems.

    The CPS - crank position sensor - had also failed, but maybe not all the time. Once these two issues were resolved, then the bike could be properly tuned for the carb & pipes. It was, and how!

    88.98 Max Hp and 104.91 Max torque, but those are just numbers. I can bury the 120mph speedo with some throttle left, and 60 - 85mph (passing on country road) in an instant. Seat o' the pants trial nearly put me off the bike.

    I hate to admit it, but it was worth the wait to have "Ol' Red" running this well...finally. I also upped the rev limiter to 6500 RPM (from stock 5800) because it still seems to have a gremlin in it. And, no, that doesn't make much sense, but it is so, just the same.

    Time for new destinations. Have commitments, for the most part, until June, then...................? Probably North, but hard to think about that in Winter.
    Fatboy128 likes this.
  2. hotroadking

    hotroadking Super Moderator Staff Member

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    Glad you found the problem and got it fixed


    Sent from my iPhone using Tapatalk
  3. badinfluence63

    badinfluence63 Well-Known Member

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    We'll... I'm glad for you but I know you sure would have liked those new M8 motors,lol.
    Red Rider likes this.
  4. Red Rider

    Red Rider Well-Known Member

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    Spoke too soon, and though the primary symptoms cleared, I still have an issue at speeds over 100MPH, but a very experienced wrenching pal & I are close to curing it. Unfortunately, I'm disappearing for an off-grid trek into our NV wilds, so probably won't get to it till late next week.

    If anyone thinks I shouldn't care about +100MPH issues, our roads here (as elsewhere in the West) are 85MPH speed limits, and sometimes one needs to get around stuff in a hurry...;)

    P.S. Yeah, BI, I know a new M8 rig would have no +100 issues, but I love my old ride too much!
  5. hotroadking

    hotroadking Super Moderator Staff Member

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    well just don't go over 99 :cool:
  6. Red Rider

    Red Rider Well-Known Member

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    I really don't think that is an option. Sometimes, the throttle just does all that it can without me even trying...or at least that is what I'd tell the judge!
  7. badinfluence63

    badinfluence63 Well-Known Member

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    Keep it and get a new one? I still have my bought new 1983 FLHS. My son has it now.

    image.jpeg
    image.jpeg
    Red Rider likes this.
  8. Red Rider

    Red Rider Well-Known Member

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    The more I learn, the more I know what I don't know. Apparently, the Crankshaft Position Sensor is not necessary with a Twin Tec TC-88 ignition. So getting it repaired/replaced was a total frickin' waste of money. More investigation is needed.....
  9. hotroadking

    hotroadking Super Moderator Staff Member

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    That is true if you are not running a stock HD ignition you can eliminate the CPS, I ran the SNS IST on my 124 Heritage (2000), Replaced the stock cam cover with a billet SNS cover to help handle the stress of the valvetrain, no CPS hole, the ECM learned that it wasn't there.
  10. hotroadking

    hotroadking Super Moderator Staff Member

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    If you have an intermittant electrical gremlin it's best to just
    take a 12 pack of beer, sit in the garage and go over the harness.

    FLH's are famous for broken wires at the neck especially on faring
    bikes, it's all a goose chase, I had a buddy that had his bike in 3 shops
    chasing down a gremiln, his bike would run strong, then it would stumble
    for no reason, it got worse, backfiring, all kinds of weird shidt.

    My heritage went through two or three ignition switches, melting
    the internals, apparently HD had a bad batch, I must have bought them all.

    Also found the main breaker had gone bad, that is common with early TC
    engines, you can replace it with one from autozone or pay the HD tax, thats
    one reason the new bikes have a 50 maxi fuse and no more main breakers.

    I had him bring it over and we discussed when and how, seems it was worse
    when raining, bingo gotta be a short somewhere water hits, took a garden hose,
    cranked up the bike, started at the regulator and worked up, as soon as I hit
    the front plug wire it backfires snorted farted and arc'd from a split plug
    wire to the head.

    The chrome covers he had on the plugs had over time with vibration cut
    a tiny, smooth slice into the back side of the wire, wasn't an issue until it got wet.

    One plug wire and it was fixed...
    Red Rider likes this.
  11. Red Rider

    Red Rider Well-Known Member

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    Thanks, HRK, all good stuff. Well, except I just mix up a batch of Jim Beam/St. Germaine/lemonade instead of beer....and don't forget the cigar.
  12. hotroadking

    hotroadking Super Moderator Staff Member

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    well yeah, cigars are a prerequisite

    Since it happens only when you are moving I'd get it up and running
    warmed up then do a wiggle test on the harness to see if you can recreate
    the problem since no error codes are being set it's probably a grounded wire
    or loose connector/connection

    Start at the ground at the battery, check the cables and work backwards.
    Red Rider and 03LD like this.
  13. Red Rider

    Red Rider Well-Known Member

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    Yep......no codes.......roger wilco.......

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