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Thread: R90/6 not starting

  1. #1
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    R90/6 not starting

    Bike has been running well all summer. For the first time today it would not start after riding it for 3 miles. When I pressed the start button there was a faint click sound. The sound seems to be coming from either under the tank or in the headlight. The horn and headlights are strong so the battery is good. Any ideas?

  2. #2
    Monza Blue 1974 R90/6
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    The starter relay or the starter.

    The wires on the starter relay are a collection point for corrosion. The red one is the important one.

    Search this forum for "starter relay" and you will get a batch of stories.

    Try cleaning all the connections at the starter relay and see if that helps.

    Also, I know you said the battery is good. But, seems like the battery is the #1 cause of electrical problems that look like they are something else.

    Finally, you have dash lights (oil, charge, neutral) as normal and everything else (blinkers, brake light, tail light) works, just nothing (except a click) when you press the starter?

    Barron

  3. #3
    Registered User lmo1131's Avatar
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    Compared to spinning over the engine, it doesn't take much poop (aka: amperage) to honk the horn or power the light.

    Easiest test: put a jumper cable to the battery and see if the problem goes away.

    Second easiest test: pull the tank and go after the relay. Look for loose wires, frayed, or nearly broken conductors, and corroded terminals
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  4. #4
    Registered User mneblett's Avatar
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    Third easiest test: Put a voltmeter across the battery terminals, then watch the battery voltage when you press the starter button. If it drops below 10V, the battery is done.

    The clicking of the starter relay is certainly pointing toward a battery on its way out. The headlight/horn working is not indicative of a good battery -- they take a few amps of current, not the 200-300 amps the starter sucks down.
    Mark Neblett
    Fairfax, VA
    #32806

  5. #5
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    Thanks for the tips. I will check it out tonight and hopefully be reporting back the solution. I love these forums. It sure beats taking my bike to the shop for things that I can do myself.

  6. #6
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    Surprisingly, tonight it started up as usual. I did a battery check and it never dropped below 10 volts and held a steady 12 volts while running. Battery is less than four months old so I never suspected that was the problem. I know what you are thinking. Yes, the starter relay may be going and I will be stranded on some lonesome road. So, I plan to park it on a hill and bump start it just in case that happens. Thanks for all the suggestions.

  7. #7
    Administrator 20774's Avatar
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    Quote Originally Posted by rbryson View Post
    held a steady 12 volts while running.
    Hmmm...that doesn't sound good. What did it read when the RPM was 3K or above? Better not be 12v...should be closer to 14v. If not near 14v, you have a charging problem.
    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!

  8. #8
    Registered User lmo1131's Avatar
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    Surprisingly, tonight it started up as usual.
    Not too surprising really. The battery developed a surface charge while resting. Make sure the battery is fully charged, if it isn't the alternator isn't going to be able to make full power. From personal experience I can say that just because the battery is new, doesn't mean that it is "good". Take it to a battery shop and have them put a "load tester" on it.

    I've been through this recently myself. Here's some background reading to start with. I've got a /5, but the diagnostic process it the same.

    http://www.bmwmoa.org/forum/showthre...ternator+check

    http://www.bmwmoa.org/forum/showthre...ternator+check

    Und, von Herr Bum...

    http://bmwmotorcycletech.info/trbleshootALT.htm
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

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