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Thread: Starting Problems

  1. #1
    Donmystic1
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    Starting Problems

    I have a 1977 R75/7 with 38000 miles.

    When I push the start button I get nothing.
    The battery is fully charged
    There are no broken wires that are readily apparent.
    Fuses look ok
    I replaced the starter solenoid with a new one.
    Prior to me replacing the push rod seals the bike started fine now I have lost a connection somewhere.

    Any ideas

    Thanks
    Don
    860-460-3282

  2. #2
    Administrator 20774's Avatar
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    Do lights on the instrument pod operate normally?
    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
    Registered User bmwbubblehead's Avatar
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    check the electrical ground

    check the electrical ground. go through everything you did, step by step and make sure it is back as it should be.

  4. #4
    Donmystic1
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    Starting problems

    Quote Originally Posted by BMWBubblehead View Post
    check the electrical ground. go through everything you did, step by step and make sure it is back as it should be.
    Everything else works as it should.
    I will have to trace the wires in the starting system.

  5. #5
    Administrator 20774's Avatar
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    Kill switch?
    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!

  6. #6
    Minnesota Nice! braddog's Avatar
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    I had a similar problem on my '77 R100RS. Fully charged, newer battery. Turned the key on, everything worked except the starter button. Shorted the starter relay, starter turned over just fine. OK, so that means something between the relay and switch, right? Turns out a wire from the handlebar switch gear had gotten "stretched" so it was no longer making good contact. I had to repair/replace some the wiring from the switchgear on the handlebars, problem solved.

    Just thought I'd share in case your issue is similar.
    -----------------------------------------
    Brad D. - Member #105766
    '77 R100RS - Black Beauty (big pipe, baby!)
    '94 R1100RS - Sylvia

  7. #7
    Monza Blue 1974 R90/6
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    Fortunately, as electrical problems go, the one you are having is generally easier because the circuit to the starter is pretty straight forward.

    However, one of the major points that keeps being validated on this forum is that an apparently fully charged and healthy battery is very often a problem.

    Can you jump the bike using another battery?

    What about checking for a voltage drop at the battery when you press the starter button? If it drops below 9 volts, that might not be enough to turn the starter.

    If the battery really is ok, then as outlined above, you can "jump" power direct to the starter and see if it turns. If so, then you can start working forward from the battery (or backwards from the starter) to find the disconnect.

    Common problem spots for a bad connection are the red wire connection at the starter relay and the red wire connection on the diode board.

    Good question (above) about whether you are having other problems like lack of dash/insturment panel lights with the ignition key on.

    Barron

  8. #8
    Registered User lmo1131's Avatar
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    Prior to me replacing the push rod seals the bike started fine now I have lost a connection somewhere.
    Common problem spots for a bad connection are the red wire connection at the starter relay and the red wire connection on the diode board.
    I'm guessing that the battery was disconnected before the push rod seal work was done?
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  9. #9
    Registered User
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    Had nearly the exact same problem with my 78 R100/7. I had just purchased it a month earlier, and barely rode it 100 miles due to the weather. Though my issue was cause by my putting it in gear before going into a restaurant (I didn't want it to roll) and when I came out, I forgot about that. Turned the key on, pushed the button, and nothing!!

    Then I remembered (it had been over 20 years since I had my previous BMW or any other bike) that it has a switch on the shifter so that it cannot be started in gear!

    Put in neutral, and away I went!

  10. #10
    Donmystic1
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    Starting problems

    I have the same problem as Braddog ( reply # 7 ).
    I jumped the starter with a screwdriver and everything is normal.
    Now I plan to cut into the wire cover coming from the starter switch and see if I have his problem.

    The easy thing would be to put a switch between the starter circuit and by pass the factory circuit.

    I spend a little more time before I do that though.

    Don

  11. #11
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    Quote Originally Posted by Donmystic1 View Post
    I have a 1977 R75/7 with 38000 miles.

    When I push the start button I get nothing.
    The battery is fully charged
    There are no broken wires that are readily apparent.
    Fuses look ok
    I replaced the starter solenoid with a new one.
    Prior to me replacing the push rod seals the bike started fine now I have lost a connection somewhere.

    Any ideas

    Thanks
    Don
    860-460-3282
    Sometimes these forums are best used to point out the obvious:

    1. The bike started fine before you worked on it.
    2. Work was done.
    3. Now, the bike does not start - translated to mean the starter does not work.
    4. The bike's starter is not defective nor is the starter relay.

    Obviously, something changed when work was done on the bike. It would be wise to reflect on what was done that could possible have caused this problem. Good luck!
    Stan

    AH# 13238

  12. #12
    Donmystic1
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    Starter wont work

    When I did the push rod seal replacement, all I did was remove the heads pull the cylinder partially out, replace the seals and reassemble. I don't see any wires that were moved or disconnected except the spark plug wires and I have checked them.

  13. #13
    . AntonLargiader's Avatar
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    Cutting into wiring should be the last resort.

    First, check the safeguards. Bike in neutral, neutral light on? Clutch squeezed. When you press the button (in a very quiet room) can you hear the starter relay click, under the tank?

    If not, start to check the power flow. Power to the start button, from the start button, to the relay, etc. You can do this in the headlight bucket and under the tank without cutting into anything.
    Anton Largiader 72724
    largiader.com bmwra.org

  14. #14
    Minnesota Nice! braddog's Avatar
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    Quote Originally Posted by AntonLargiader View Post
    Cutting into wiring should be the last resort.

    First, check the safeguards. Bike in neutral, neutral light on? Clutch squeezed. When you press the button (in a very quiet room) can you hear the starter relay click, under the tank?

    If not, start to check the power flow. Power to the start button, from the start button, to the relay, etc. You can do this in the headlight bucket and under the tank without cutting into anything.
    Correct. We did all of our troubleshooting with a simple circuit tester, we didn't cut into anything.
    -----------------------------------------
    Brad D. - Member #105766
    '77 R100RS - Black Beauty (big pipe, baby!)
    '94 R1100RS - Sylvia

  15. #15
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    My '77 R100S had a similar problem, however it would start with the clutch pulled, so if you are certain that function always worked in the past then ignore this.

    There is a diode on the terminal board (not the diode board) that can fail. It is a bear to get to at the back of the headlight bucket. The Haynes wiring diagram shows this on terminal 85B. FYI my neutral light did work also. Guys at RePsycle walked me through this problem!

    I believe you should be able to test the diode function without too much disassembly?

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