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Thread: Starter engaging when running?

  1. #1

    Starter engaging when running?

    Good morning, recently it seemed like my starter was engaging while my R75/5 was running...I'd hear a brief clatter - it seems to be coming from the left side ...I know that a failing relay could cause that, so I bought new one. I also cleaned my handlebar switch, best I could, but it still seems like it's kicking in...could the switch be failing and triggering the starter? Or what else could it be?

    thanks Chuck
    C R NY
    1972 R75/5
    1969 2002
    1982 528e

  2. #2
    Quote Originally Posted by crouthier View Post
    Good morning, recently it seemed like my starter was engaging while my R75/5 was running...I'd hear a brief clatter - it seems to be coming from the left side ...I know that a failing relay could cause that, so I bought new one. I also cleaned my handlebar switch, best I could, but it still seems like it's kicking in...could the switch be failing and triggering the starter? Or what else could it be?

    thanks Chuck
    Disable the switch and that might tell you something. I had the same problem, replaced the relay. Had to replace the second new relay. it was no good as well.

  3. #3
    great suggestion...I'll try that. I replaced my regulator - twice - as first new one was bad...happens a lot!

    C
    C R NY
    1972 R75/5
    1969 2002
    1982 528e

  4. #4
    Liaison 20774's Avatar
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    The starter is located more or less in the front and right side of the top of the engine, so that's where the sound might come from...of course, if the starter throws out the pinion for starting, it will have the teeth clack against the flywheel...that would be a sound right between your legs.

    The starter relay is on the left side under the tank. Seems like it would be hard to hear over a running engine, but not sure. What type of relay did you use? Ideally, OEM relays should be used in this situation as they have all of the functions built in.

    Could you possibly have the "Cricket" noise? Snowbum mentions it on this page:

    http://bmwmotorcycletech.info/electricalhints.htm
    Kurt -- Forum Liaison ---> 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!

  5. #5
    Hi Kurt, I used a Euro Motoelectric replacement relay. It sounds like a brief metallic 'clatter' (perhaps not quite as loud as the starter?) - I just read the Snowbum article and it could very well be the 'cricket' sound as he describes it as a 'clackety clack' sound... but not really sure. The sound 'seems ' like it's coming from the left. The Euro relays says it has a lock out to prevent the starter from engaging while the bike is running so there could be something else wrong with either my charging system or with the relay.

    thanks, Chuck
    Last edited by crouthier; 05-22-2019 at 06:32 PM.
    C R NY
    1972 R75/5
    1969 2002
    1982 528e

  6. #6
    Update: It looks like the relay may be bad. According to Euro M, if there is power at the blue wires and bike starts and charges, it must be the relay...I'll have to look at a wiring diagram, but in my few tests: I have power at one of the blue wires going into the relay, and if I unplug the other blue wire, bike won't fire. If I disconnect a blue wire, the bike won't charge...c
    C R NY
    1972 R75/5
    1969 2002
    1982 528e

  7. #7
    Liaison 20774's Avatar
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    Strange that basic relays can be bad...guess it happens. Is the part 12411350775?
    Kurt -- Forum Liaison ---> 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
    Hi Kurt, the orig part no = 1 350 775 as is the new one. I guess I am perplexed on how this locks out the starter. It is suppose to function that when running the starter should NOT engage, even if you hit the starter button?

    I was def getting some odd chatter, or clacking sounds from the orig AND the new one...symptoms of a failing orig /5 relay.

    C
    C R NY
    1972 R75/5
    1969 2002
    1982 528e

  9. #9
    Liaison 20774's Avatar
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    Chuck -

    I could be wrong, but the starter relay isn't part of any lockout circuit....special note below. The primary purpose of the relay is to get a signal from the handlebar switch...the signal is 12v over smallish wires. The 12v causes a coil inside the relay to pull and latch a set of contacts which directs 12v to the starter solenoid using heavy wires, since it will be delivered large amps. There are other things on the bike to prevent the relay from latching when the engine is running. One is the transmission neutral switch...if you're in neutral, the starter can be engaged. The other is a switch in the clutch lever up on the handlebars...when the hand lever is pulled in, it should prevent the starter from being engage. This second one can be useful if for some reason you kill the engine at an intersection...you can put the bike in gear, or much easier, just grab some clutch and hit the starter button.

    Snowbum actually characterizes the /5 starter relay as a "lockout relay". He mentions that this relay for the /5 has a special transistor circuit:

    http://bmwmotorcycletech.info/slash5cricket.htm

    This feature or issue on the /5 was fixed in later models such that the relay wasn't a lockout relay but worked as I described above.
    Kurt -- Forum Liaison ---> 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!

  10. #10
    Thanks Kurt, I did read that Snowbum page, or most of it, and need to re-read. But it does seem like the /5 relay, and only the /5 relay, not newer bikes, have the lockout through a transistor circuit IN the relay, not using neutral / clutch. And from what I gather it's based on RPM and the charging system, so at low RPM the lockout may not work...

    I am getting a new relay anyway and will see what's up...thank you! Chuck
    C R NY
    1972 R75/5
    1969 2002
    1982 528e

  11. #11
    B Reams brook.reams's Avatar
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    Quote Originally Posted by crouthier View Post
    Thanks Kurt, I did read that Snowbum page, or most of it, and need to re-read. But it does seem like the /5 relay, and only the /5 relay, not newer bikes, have the lockout through a transistor circuit IN the relay, not using neutral / clutch. And from what I gather it's based on RPM and the charging system, so at low RPM the lockout may not work...

    I am getting a new relay anyway and will see what's up...thank you! Chuck
    Hi Crouthier,

    Yes, you are correct that the /5 bike starter relay design attempts to lock out the starter motor when the engine is running. There is a transistor and resistors inside that sense current flow from the alternator. If sufficient, it opens the transistor preventing power to flow through the starter relay to the starter solenoid.

    You can read more about this here:




    BTW, should the starter motor actually engage the flywheel when the engine is running, bad things can happen quickly.

    The "crickets" problem is caused by too low a battery voltage. This occurs when you try to start the bike, not while it is running. With a low battery and a very cold day, you can get this situation.

    I hope this helps.

    Best.
    Brook Reams.
    Last edited by brook.reams; 05-23-2019 at 08:03 PM.
    Brook Reams - Arvada, CO
    Endeavor to Persevere
    Various Two-wheeled Vices, All BMW || Website: Airhead Rebuild Projects
    2004 R1150-RS||2002 F650-GS||1983 R100RS||1977 R100RS||1973 R75/5

  12. #12
    Quote Originally Posted by brook.reams View Post
    Hi Crouthier,

    Yes, you are correct that the /5 bike starter relay design attempts to lock out the starter motor when the engine is running. There is a transistor and resistors inside that sense current flow from the alternator. If sufficient, it opens the transistor preventing power to flow through the starter relay to the starter solenoid.

    You can read more about this here:




    BTW, should the start motor actually engage the flywheel when the engine is running, bad things can happen quickly.

    The "crickets" problem is caused by too low a battery voltage. This occurs when you try to start the bike, not while it is running. With a low battery and a very cold day, you can get this situation.

    I hope this helps.

    Best.
    Brook Reams.
    Following up on what Brook says. Unless, in recent years, the starter relay has gone from mechanical to electronic, I have had the situation where the points inside the relay arc and burn together, causing a "continuous on" situation with the current to the starter.
    Also, to get rid of the /5 starter "cricket" I recall once installing a diode on the blue circuit, I believe, to prevent some kind of a voltage dump and low solenoid signal. It's been a while but I believe there is a thread on the BMW Rider's website dealing with this"cricket" cure. The only thing I am really sure of is that, after that, I haven't had the problem in a few years.

  13. #13
    Hi Brook, thank you for your response. I DID look at your blog pages, super helpful. I had a situation on a previous /5 (20 years ago) where the relay failed in such a way as to fire the starter while the bike was running. I'm not sure that's whats happening with mine, but it IS doing something similar - sounds like the starter is engaging with bike running. I took my original relay apart and there is a lot of corrosion at the D+ connections...the replacement relay definitely allows the starter to operate while the bike is running...

    thanks Chuck
    C R NY
    1972 R75/5
    1969 2002
    1982 528e

  14. #14
    '99 '03 '06 National Co-Rally Chair Friedle's Avatar
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    Quote Originally Posted by crouthier View Post
    Hi Brook, thank you for your response. I DID look at your blog pages, super helpful. I had a situation on a previous /5 (20 years ago) where the relay failed in such a way as to fire the starter while the bike was running. I'm not sure that's whats happening with mine, but it IS doing something similar - sounds like the starter is engaging with bike running. I took my original relay apart and there is a lot of corrosion at the D+ connections...the replacement relay definitely allows the starter to operate while the bike is running...

    thanks Chuck
    If your replacement relay allows the starter to engage while the motor is running, it is NOT the correct stock /5 starter relay.

    Friedle
    Ride fast safely

  15. #15
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    Hi Chuck, I echo to the same advice given by most members. I too have posted my R75 starter issue in this forum and received help -- in my case it was truly due to the Relay - even though it is a brand new relay (factory from germany). This was documented in Snowbum's journal as well. I proceeded to do the soldering and that fixed the issue. Here is my previous posting for your interest: https://forums.bmwmoa.org/showthread...one&highlight=

    Good luck,
    Henry

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