Starter problems?

Discussion in 'Airheads' started by GCCR, May 27, 2013.

  1. GCCR

    GCCR Been here awhile

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    Greetings,

    I was hoping someone could chime in on this one. I have a 78 R100/7 that recently started to click-click-click when trying to start it. At times it will start, but same thing after i turn the ignition off and back on again. A few days later I noticed that I had a wire running back to my taillight that the sheathing started to bubble and melt. I didn't put the two together until today as I tried starting the bike again. I recently removed the cylinders and heads to do a pushrod seal replacement. As I tried to start it up I heard the same clicking, but this time since I had the tail piece off the bike I could see the wire start to smoke. I looked inside the headlight bucket and found one loose ground wire; I tightened it, and checked the fuses. All good, but same problem persists. I have to admit I'm not a good wiring guy. I am also running a Shorai battery on this, mounted under the rear seat cowl. Any ideas?

    Cheers,

    Dan
    #1
  2. Bulldust

    Bulldust Bulldust

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    Check all your earth connections, sounds like it is trying to earth through the tail light wire.
    #2
  3. disston

    disston ShadeTreeExpert

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    The starter relay should be under the tank. On my /6 it is on the left side. It has a lot of wires going to it. Remove wires and clean well, apply dielectric grease if you have any. Remove and reinstall each wire several times to make it contact.

    As a general rule you should clean all the wires you can reach. Not sure why the tail light is smoking at the same time though. You are in danger of having a fire you know? And if it doesn't burn up letting the smoke out of the wires is not good.

    So go over all these changes you have done and check the wires. The grounds are brown wires. Look for a bunch of them bolted to the frame. Clean and tighten.

    Did you change the wiring much when you moved the battery?
    #3
  4. GCCR

    GCCR Been here awhile

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    The modifications were a bit extensive. Wired i an Acewell gauge, new tailight, and all indicator lights. I'll go through it again. Thanks
    #4
  5. GCCR

    GCCR Been here awhile

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    Thank you, I'll go through them as best I can.
    #5
  6. disston

    disston ShadeTreeExpert

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    The suggestion from Bulldust is the clue you need. There has to be a hot wire and a ground souce for anything electrical. When the grounds are screwed up the electricity will go through other things to reach the ground on the other side. Since the tail light can't handle all the current needed by the starter the starter clicks.

    The starter grounds through the engine case doesn't it? Check the ground wire connection from your battery.
    #6
  7. GCCR

    GCCR Been here awhile

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    The battery grounds to the frame. and the Starter grounds to the case. What is perplexing is that this hasn't been an issue until now. The bike started, and ran fine for a year. I can't recall making any changes in the interim.
    #7
  8. disston

    disston ShadeTreeExpert

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    It could be the ground that runs the relay. It could be a frayed wire inside a harness. Two wires shorted to each other. The possibilities are endless so we always suggest the check everything routine.
    #8
  9. GCCR

    GCCR Been here awhile

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    I peeled back the main sheathing on the rear wiring loom for the rear lights and found this ground wire in a bad way. It was frayed at the very end of the bubbled wire sheathing. I disconnect the rear loom and it fires right up. I can't understand how the sheathing exposed the wire to cause this. Now to fix it. Thanks guys for the ideas. [​IMG]

    Dan
    #9
  10. Warin

    Warin Retired

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    I'd recommend you run ONE large ground wire from the battery to the gearbox breather bolt ('Fred'). Large as in diameter.

    Do not run any other wires to the battery negative terminal. This will stop any faults on the battery ground side from burning up your wiring harness and possibly setting fire to your bike...
    #10
  11. GCCR

    GCCR Been here awhile

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    The battery ground wire is grounded currently to the frame where the subframe connects to the main frame. There are no other wires connected to the battery. The brown thin ground wire ran from the rear harness connector and grounded on the frame under the seat. Is that an issue?
    #11
  12. _cy_

    _cy_ Long timer

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    what size Shorai? what is the resting voltage? after battery sits overnight measured with a known to be correct meter. cheap $15 meters are fine, if it's been tested against a known to be correct meter like a Fluke. otherwise results are suspect until measured with a known to be correct meter.

    LiFePO4 operating voltage range are very narrow ... 13.3v to 12.85v ... about 1/2 volt difference for about 90% of total capacity. hence need for an accurate meter.

    under sizing LiFePO4 batteries are a chronic problem. especially for airheads which has much higher amp hour requirements. especially if airhead is to be started at colder temps.

    don't believe marketing speak of PB/EQ or lead acid equivalent. what counts is actual amp hour ratings for LiFePO4 batteries and what happens when a sustained 200amp+ load is placed on battery?

    with engine rev'd up to 3500 rpm ... output measured at battery should be 13.8v to 14.2v or your LiFePO4 or PB battery will not charge at normal rate. LiFePO4 prefers charge rate at upper end of normal. max charge rate for LiFePo4 should not exceed 14.6v

    if your bike is charging below 13.8v, your LiFePO4 battery take forever to reach full charge, which is unacceptable for a battery with a tiny amp hour capacity ... something is wrong and should be chased down. look for corrosion in your B+ wire, check ground wire to diode, etc. mechanical regulators are suspect and should be check by swapping out with another regulator. some mechanical regulators can be adjusted up, but it's probably easier to replace with a solid state version. a higher voltage version is available.

    LOTS more info in battery testing thread .. link in sig
    #12
  13. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    Nonethless, it appears that the starter is trying to ground itself through that chassis ground wire. Ground the battery directly to the engine/transmission.

    --Bill
    #13
  14. GCCR

    GCCR Been here awhile

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    Thanks, I'll do that.
    #14