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Thread: 86 K75 Starter Issues

  1. #1
    86 K75 chassis 114638
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    86 K75 Starter Issues

    Happy New Year, everyone

    Thanks to the great replies I received in my previous problem on my K, that of my radiator fan motor which seized. The tips that helped me in getting it replaced and gives peace of mind this coming summer. I'm hoping to attend the Salem rally in July so maybe I'll be fortunate to run into some of you.

    My latest problem is to do with my starter. During the summer, the starter motor seemed to jam and a few raps on it seemed to free it. I read that the likely culprit was the sprag clutch and a couple of doses of rislone may help to counter this stickiness. The problem did not completely go away and the odd time, I would have to free the starter with a few more sharp wraps.

    Unfortunately, tonight, the treatment didn't work. When I walked out of work tonight in the pouring near freezing rain of Vancouver, the starter motor may have packed it in. The whirr of the motor seemed a little higher in pitch and after a couple of un-successful attempts, I now get nothing (whirr, whine, belch) nothing when I press the ignition. So my main question is, can I replace part of this starter or must I install a completely new starter? I've watched a helpful Youtube video on replacing the brushes on the starter motor but because I am not as familiar with this topic as most of you, I'm hoping I can read some good replies and tips.

    Oh, I was able to get a friend at work to push the bike and successfully bump started the K and got myself home. I now have to decide to bring it into the shop or try to do this fix myself.

    Thank you for reading my post.

    Sunny

  2. #2
    Registered User Beemer01's Avatar
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    Starter issues

    Replacing the starter itself is a trivial exercise - lots of used units available. I did that rather then try and work on the brushes.

    The sticking Sprag clutch is a more difficult issue. This is an internal part, so access requires a lot of work.

    I had the sticking sprag clutch problem on my 85 K100 - used CD2 additive - might be the same as rislone - but was told to run her long and hard after adding the CD2. Added it - rode for a couple of hours - paying attention to keeping the Revs high. Permanently solved my sprag problem.

    Others wiser than me will weigh in.

  3. #3
    Benchwrenching PGlaves's Avatar
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    If rapping on the starter made any difference, the sprag clutch has nothing to do with it. The sprag clutch is located six inches away up on the other side of the engine auxiliary case.

    A binding starter that responds to rapping on it signals a worn nose bushing and dragging armature. Removing the starter requires getting a few things out of the way, disconnecting the wiring, removing two capscrews, and a firm tug rearward.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://www.bigbend.net/users/glaves

  4. #4
    3 Red Bricks
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    [QUOTE=EuroK75;848560 the starter motor seemed to jam
    [/QUOTE]

    A bad sprag clutch would let the starter spin without turning the engine over.

    A starter starting to turn the engine and then stopping could be:

    Bad starter (bushings or brushes) Since rapping on it seems to help, like Paul said, this seems likely

    Bad battery

    Bad connections (battery, relay, starter)



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  5. #5
    86 K75 chassis 114638
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    Replace starter or try to clean/re-install

    Thanks Paul and Lee
    This is a case of my math adding one and one together to get 3. I erred in thinking that the high mileage on this K was contributing to the sprag clutch.

    Used starters on ebay can be purchased for under $100 and am not sure what the cost of starter parts would be. Any recommendations on whether to rebuild or replace?

    Thanks
    Sunny

  6. #6
    Benchwrenching PGlaves's Avatar
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    I would pull it out, mark the three parts - nose cap, body and end cap - and take it apart. I suspect the nose bearing. The entire nose cap with bearing and O ring is available as a separate part from BMW. I have replaced a couple of them over the years. You can tell by looking and wiggling if that bushing is worn. Also examine the armature for marks from dragging.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://www.bigbend.net/users/glaves

  7. #7
    3 Red Bricks
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    Read: http://www.bmwmoa.org/forum/showthre...-1992-BMW-K75S

    Brushes are cheap:

    12 41 1 459 567 SET: CARBON BRUSH SET $13.65 (this is only one of the two brushes that you would need)

    12 41 1 459 297 BRUSH HOLDER PLATE $11.95 (this is the other brush and the holder plate)


    Anything more than that, you'll probably want to pick up a good used starter for under $50 on ebay and put the new brushes in it.



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  8. #8
    PeteG
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    If sprag clutch treatment is needed

    Hi Sunny,

    If it turns out that your issue is a sprague clutch you can read this archived thread.

    http://www.bmwmoa.org/forum/showthre...eatment-update

    It involves spray treating the clutch from the crankcase side. I had a 100% stuck sprague clutch and with this treatment AND regular CD2 treatments between oil changes the problem has remained solved for almost 2 years and 30,000+ miles.

    Typically I'll get a free spin or two when the synthetic oil gets about 5,500 miles on it. Then I top off my oil with CD2 and take her for a long freeway ride (150 to 200 miles), then change oil. I'm then good for another 5,000 or so miles. My normal oil and filter change interval is between 5,500 and 6,000 miles.

    It hasn't worked for everyone, but you may find this worth the attempt before a major tear down and sprague clutch replacement. You may also want to check your oil for metal particles. If the sprag clutch is breaking up, then replacement will be necessary.

    Hopefully the issue is just with your starter. Logic dictates that attending to the easiest repairs (starter) first is a real time saver in the long run.

    Good luck,
    Pete

  9. #9
    86 K75 chassis 114638
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    I ordered the new brush sets and plate

    Thank you all for understanding my problem and offering your expertise and experience.

    Pete, thanks for the specific info on the sprague clutch. I hope by fixing the starter next week, I'll be able to be back on the road.

    Sunny

  10. #10
    86 K75 chassis 114638
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    1986 K75 intermittent starting, continuing saga

    Hi, I wanted to update my current situation and seek more advise.

    I replaced the brushes and brush plate on starter#1. Well it seems like all the bashing on the side of the starter over the summer caused one of the four magnets to loosen from the wall . Pulled the starter again, cleaned again, and used some JB weld to hold the magnet back in place. It continued to be intermittent starting and I've now become pretty good and pushing my bike down the block uphill to bumpstart the bike. Neighbours are probably giggling at me by now.

    I made the decision to purchase a used starter#2 and installed it running the last month on my K that I've now affectionately named Bert. I wanted to take starter #2 apart to clean but the bolt heads are a different size and my socket would not fit deep enough to get a good grip. This weekend, I intend to get the correct tool accessory and do a proper cleaning.

    I'm jumping around in my story a bit but just wanted to highlight some pertinent facts to perhaps help in trouble shooting my problem that is:
    On occasion, I still need to bumpstart Bert and after riding a bit, I part him and I can tell if he will need a bumpstart because things are normal when I turn off the ignition and I hear a distinct 'clunk' from underneath the bike. If I don't, as soon as I try to restart him, I will hear the whirring of the starter but the engine will not kick over.

    Other things I've done correctly and incorrectly:
    • -Ran car engine oil 10/40 for about a year WHOOPS
      -added Rislone engine treatment (not sure if I purchased the recommended one, see next line)
      -added Rislone engine treatment "Concentrated", took Bert for a 100+ mile ride last night making sure I to ride part of the way at 5000+ RPMs
      -changed oil regularly but about a year ago back to bike oil.


    I really want to get Bert working because if I take him on a ferry and have to stop, he's not going to be reliable come startup.
    Welcome your feedback (and loud heckles if you are into that sort of thing)

    Thank you

    Sunny

  11. #11
    PeteG
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    Quote Originally Posted by EuroK75 View Post
    Hi, I wanted to update my current situation and seek more advise.

    I replaced the brushes and brush plate on starter#1. Well it seems like all the bashing on the side of the starter over the summer caused one of the four magnets to loosen from the wall . Pulled the starter again, cleaned again, and used some JB weld to hold the magnet back in place. It continued to be intermittent starting and I've now become pretty good and pushing my bike down the block uphill to bumpstart the bike. Neighbours are probably giggling at me by now.

    I made the decision to purchase a used starter#2 and installed it running the last month on my K that I've now affectionately named Bert. I wanted to take starter #2 apart to clean but the bolt heads are a different size and my socket would not fit deep enough to get a good grip. This weekend, I intend to get the correct tool accessory and do a proper cleaning.

    I'm jumping around in my story a bit but just wanted to highlight some pertinent facts to perhaps help in trouble shooting my problem that is:
    On occasion, I still need to bumpstart Bert and after riding a bit, I part him and I can tell if he will need a bumpstart because things are normal when I turn off the ignition and I hear a distinct 'clunk' from underneath the bike. If I don't, as soon as I try to restart him, I will hear the whirring of the starter but the engine will not kick over.

    Other things I've done correctly and incorrectly:
    • -Ran car engine oil 10/40 for about a year WHOOPS
      -added Rislone engine treatment (not sure if I purchased the recommended one, see next line)
      -added Rislone engine treatment "Concentrated", took Bert for a 100+ mile ride last night making sure I to ride part of the way at 5000+ RPMs
      -changed oil regularly but about a year ago back to bike oil.


    I really want to get Bert working because if I take him on a ferry and have to stop, he's not going to be reliable come startup.
    Welcome your feedback (and loud heckles if you are into that sort of thing)

    Thank you

    Sunny
    Sunny, Bert's symptoms are sounding more and more like a sprague clutch problem. Let 98lee or P Glaves weigh in on the issue as they know far more than I. To me, starter spinning without start or engine crank = sticking sprague clutch.

    My earlier post on sprague clutch treatment is one of several possible "treatments".

    You'll get him starting reliably again. Can't miss with this forum.

    Pete

  12. #12
    86 K75 chassis 114638
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    Quote Originally Posted by pjar View Post
    Sunny, Bert's symptoms are sounding more and more like a sprague clutch problem. Let 98lee or P Glaves weigh in on the issue as they know far more than I. To me, starter spinning without start or engine crank = sticking sprague clutch.

    My earlier post on sprague clutch treatment is one of several possible "treatments".

    You'll get him starting reliably again. Can't miss with this forum.

    Pete
    Thanks, Pete

    Paul wrote a great article this month covering the sprague clutch problem this month describing 2 engine cleaners. Rislone is available in the Vancouver, BC area but I wanted to try the other CD2 but it's not available in my area. After I finish this bottle, I'll probably head down to Bellingham WA to find a bottle of CD2.

    Cheers,
    Sunny

  13. #13
    3 Red Bricks
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    Quote Originally Posted by EuroK75 View Post

    On occasion, I still need to bumpstart Bert and after riding a bit, I part him and I can tell if he will need a bumpstart because things are normal when I turn off the ignition and I hear a distinct 'clunk' from underneath the bike. If I don't, as soon as I try to restart him, I will hear the whirring of the starter but the engine will not kick over.
    That IS a sprag clutch sticking. When you here the "clunk" that is the sprag clutch rollers falling into place for the next start. When you don't hear the "clunk", that means the rollers have stuck in the run (not start) position. When you hit the starter button, the starter motor runs, but is not connected through the sprag clutch to the engine, so no start.

    What CAUSES/CAUSED the sprag clutch to stick is a build up of gum and varnish caused by running oil with inadequate detergent, not frequent enough oil changes, or lots of short trips at low rpm (not getting the hot oil slinging around the sprag clutch. Usually dirty oil is the culprit.

    Not all engine "treatments" are the same. You want something that is designed to "free sticky lifters". Sticky lifters are caused by the same gum and varnish that cause the sprag clutch to stick. These treatments are generally very concentrated detergents and solvents.


    The sign of a starter problem is different. If the starter is spinning, the problem is not the starter. If the starter is NOT spinning then the problem COULD be the starter. But that does not sound like your problem.



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  14. #14
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    Free spinning Sprague sometimes

    pjar said, "Typically I'll get a free spin or two when the synthetic oil gets about 5,500 miles on it. Then I top off my oil with CD2 and take her for a long freeway ride (150 to 200 miles), then change oil. I'm then good for another 5,000 or so miles. My normal oil and filter change interval is between 5,500 and 6,000 miles."

    My 85 K100RS w 146kmiles does the exact same thing with Spectro Golden IV 20w50 near Phila. Just in case this is news: When it free spins, usually at a gas station, I point bike slightly down hill, put it in 2nd gear, roll it forward, press the starter button to free spin, then let the clutch out. Somehow I always get it to start, even 2 up. My theory on pushing the starter button, it that something of a jolt to it when you let the clutch out, helps it grab better the next time you want to use the starter's sprague clutch.

  15. #15
    86 K75 chassis 114638
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    Happy Day... I think the sprague clutch is un-stuck

    Quote Originally Posted by 98lee View Post
    That IS a sprag clutch sticking. When you here the "clunk" that is the sprag clutch rollers falling into place for the next start. When you don't hear the "clunk", that means the rollers have stuck in the run (not start) position. When you hit the starter button, the starter motor runs, but is not connected through the sprag clutch to the engine, so no start.

    What CAUSES/CAUSED the sprag clutch to stick is a build up of gum and varnish caused by running oil with inadequate detergent, not frequent enough oil changes, or lots of short trips at low rpm (not getting the hot oil slinging around the sprag clutch. Usually dirty oil is the culprit.

    Not all engine "treatments" are the same. You want something that is designed to "free sticky lifters". Sticky lifters are caused by the same gum and varnish that cause the sprag clutch to stick. These treatments are generally very concentrated detergents and solvents.


    The sign of a starter problem is different. If the starter is spinning, the problem is not the starter. If the starter is NOT spinning then the problem COULD be the starter. But that does not sound like your problem.



    Thank you again, Don and Pete

    I really wanted to give the bike a chance to drain all the oil completely so I gave Bert a hard workout on Friday night. Immediately after I got home, I opened up the plug and oil filter cover and let Bert relieve himself all night long giving all the old oil a chance to settle. On Saturday morning, I popped in the new oil, oil filter, with a healthy dose of Rislone, Bert shot to life without any problems. I took him out a few times today and every single time, the magical sound of the clunk was heard when I parked Bert.

    So thanks again for everyone's advice on the sprague clutch. While I only put about 3500km since the last change, it's been 6 months since the last oil change.

    From now on, I'll make sure I watch the interval between oil changes, run the bike at higher RPM from time to time, and regularly treat Bert to engine treatment.


    Sunny

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