Is my starter going?

Discussion in 'Airheads' started by mfp4073, Sep 15, 2012.

  1. mfp4073

    mfp4073 Long timer

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    thanks for all the replies

    The trick that was missing was what crazydrummerdude mentioned. You have to put 12v to the spade connector in addition to the main positive.

    So here were my tests today, tested it on the bench with a battery providing power. Seemed like it wound up ok, but my suspicion is the bearings are going. Seemed like it wound down to fast and was "vibrating" a bit more than I would have expected during wind down. I got none of the solenoid clicking.

    Next test, lay it on the engine, hook up batter and starter and test it with the bikes starting system. Same result. At this point started to think that there was a contact issue that I disturbed and it "fixed itself"

    Put bike back together with the idea that the starter needs replacing due to the bearing/wind down feel, but that I had fixed the problem. Yeah, no. Went back to the old turnover, clicking, turnover, clicking thing.

    GRRRRRRR.
    #21
  2. Wirespokes

    Wirespokes Beemerholics Anonymous

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    I think it needs the bushings replaced.
    #22
  3. mfp4073

    mfp4073 Long timer

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    Even if everything else were normal, I would agree to this statement.
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  4. Sergeant Joe

    Sergeant Joe Sitrep=Snafu

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    Bad earth is the culprit 95% of the time. Just saying :1drink
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  5. mfp4073

    mfp4073 Long timer

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    here is a strange update......

    As listed I got the bike/starter apart and everything tested normal as best as I could test. Still go the clicking and not "catching" and cranking like it should.

    I was going to next look at battery cables, but didnt get the time as my alternator rotor failed and had to be replaced.

    Here is the strange part. In the last 2 days since I have had the bike back on the road with a new rotor/brushes in it I dont get the clicking solenoid anymore. I dont get it myself? How can the two be related? :huh
    #25
  6. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Does this mean the starter is working normally with no clicking solenoid, or...

    When you press the starter button you don't get anything, not even get clicking?
    #26
  7. mfp4073

    mfp4073 Long timer

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    Sorry about that. Yeah, its working normally. Odd huh?
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  8. Wirespokes

    Wirespokes Beemerholics Anonymous

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    Sounds like the battery was low, and the root of the problem was the failing rotor.
    #28
  9. mfp4073

    mfp4073 Long timer

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    When this was happening, I was charging and testing the battery regularly to make sure it was not low because that was my first thought. Cant imagine the battery being low for several months at a time?
    #29
  10. chasbmw

    chasbmw Long timer

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    if the starter only gives problems when it is under load, then ther problem is often due to wear in the bushings, this allows the armature to cock sideways under load and everything starts to go really slow.

    I dont know if the bushs are available for these old 8 tooth Boschs, but given that you can buy either Valeo or Nippon Denso 8 tooth starter motors nowadays I would go for replacement.
    #30
  11. disston

    disston ShadeTreeExpert

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    The bushings are available several places. Motorad Electrik comes to mind.

    The only part that I think I see reports about not being able to buy is the early 8 tooth pinion. These reports are rather universal however I'm not really sure that there isn't some obscure source, it's a Bosch part after all, or there isn't some way to make do, adapt, another 8 tooth pinion to the Bosch starter Armature.

    If you need the 8 tooth pinion it doesn't look hopeful.
    #31
  12. chasbmw

    chasbmw Long timer

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    The guy at motor works in the UK that rebuild Bosch starters said that the solenoids were NLA.

    If the bike was mine I would replace with valeo, they work well
    #32
  13. mfp4073

    mfp4073 Long timer

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    What do I have to do to use one of the 9 tooth valeo starters with my 8 tooth setup?

    (although the question may be moot as its working properly now)
    #33
  14. disston

    disston ShadeTreeExpert

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    Change the flywheel to one that uses a 9 tooth starter. Since they also changed to the 11 mm flywheel bolts change the crank shaft.

    It's a big job and you would need help and extra money. Much easier to buy another engine.
    #34
  15. mfp4073

    mfp4073 Long timer

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    Or pick up a new 8 tooth starter :huh
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  16. chasbmw

    chasbmw Long timer

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    Don't make the mistake of trying to use a 9 tooth starter on an 8 tooth flywheel as you will ruin the teeth on the flywheel

    I have heard of people fitting the later 9 tooth flywheel to the earlier bikes, they use sleeves on the flywheel bolt holes, so that they can use the original sized flywheel bolts. By the account I heard this worked well.

    It's really good that we can get new starters for 42 year old bikes!
    #36
  17. DoktorT

    DoktorT BigBrowedNeandereer

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    Must say, even after rereading this thread. I never saw anywhere where either batteries old or new were properly load tested to verify good rebound.

    I just think spending any time at all doing other than that is unwise. Go back and verify resting volts, volt drop when hitting the starter, then rebound volts after a few minutes rest. Those numbers tell where to go for faults and key to finding culprits.

    I have indeed seen NEW batteries that do not meet specs. Though rare, a load test can prove the right in every case.

    Once that's done, then you can confirm what the charging systems is doing. Get that spec.

    THEN check the starter relay and starter.

    Sometimes on an poorly serviced airhead you can find weakenesses as you go everywhere through the machine. It's a synergy of weaknesses adding up to poor and non function.

    But if you assume a new battery is good then go on about troubleshooting for days and weeks, best get back to PROOF of VOLTS/AMPS in the battery. Has not yet been as far as I could find. A multimeter and 5 minutes is all that is needed to rule out the battery as a contributor in the equation.
    #37
  18. mfp4073

    mfp4073 Long timer

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    Ok, lets start over here. Cliff note style

    starter was clicking (off and on, not consistent), did some testing, took it apart and bench tested, etc

    put it back together, same thing.

    Alternator rotor failed.

    Alternator rotor replaced.

    Now not clicking unless I have been messing around and battery is low.

    Currently I can test whatever with the starter and the battery....but its acting normal as if the problem has solved itself.

    So again, most recent question. Any ideas on why a new rotor would effect the starter circuit?
    #38
  19. DoktorT

    DoktorT BigBrowedNeandereer

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    You still haven't proved the battery via a standard load test. Tell us current static volts at rest, volts when start button held for 5 seconds, then rebound static volts after some 5 miutes rest. Rule this out with a very quick and simple test, rather than speculations on other evidence that depends upon volts/amps available. Nothing downline can do it's job if the power supply is weak, so rule that out with just a simple, standard load test.
    #39
  20. Wirespokes

    Wirespokes Beemerholics Anonymous

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    When the battery is weak, it doesn't have enough power to turn the starter motor, PLUS operate the starter relay or starter solenoid.

    So then the starter solenoid opens up - CLICK!

    Once it opens, and the starter motor is out of the circuit, there's again enough battery power to power the solenoid and relay. CLICK!

    Once the starter starts turning, battery power to the solenoid drops and CLICK! it opens and the cycle repeats.

    When diagnosing these things you have the question: is it the solenoid? starter? battery?

    The starter can draw way too much current (when needing a rebuild) and pull so much from the battery it can cause this phenomenon.

    A bad relay that won't handle much current can do this.

    Or, a bad battery with low capacity, or just not sufficiently charged can cause the same scenario.

    In your case, it's now working after replacing the rotor, so obviously the battery wasn't getting sufficiently charged previously. I see no other explanation for what's happened. I have no answer why a volt reading would have told you it was fine, yet wouldn't crank the engine. But it seems obvious to me the battery wasn't filled previously to capacity.
    #40