Page 1 of 2 1 2 LastLast
Results 1 to 15 of 16

Thread: '85 K100RS handling question

  1. #1
    Registered User
    Join Date
    Feb 2018
    Location
    Sturgeon Bay WI
    Posts
    22

    '85 K100RS handling question

    Hi everybody,
    so I just acquired a 1985 K100RS with lotsa miles on it (251k). Bike has a great maintenance history and runs well (except a rattle at cold startup- another topic). Here is what I observed today: at 60 mph I am downshifting from 4th to 3rd and when I briefly let go of the handlebars to see how the bike is balanced a wobble starts in the front wheel and it builds very rapidly. As soon as I hold the bars it disappears. No wobble can be felt in any other condition. Only when bike decelerates in that tempo range and when I let go of the bars. Now you may ask, why do you let go of the bars? I usually don't but none of my other 3 beemers do this. Is this a design issue with the K100RS? Any other ideas? Thanks.

  2. #2
    Quote Originally Posted by allemande View Post
    Hi everybody,
    so I just acquired a 1985 K100RS with lotsa miles on it (251k). Bike has a great maintenance history and runs well (except a rattle at cold startup- another topic). Here is what I observed today: at 60 mph I am downshifting from 4th to 3rd and when I briefly let go of the handlebars to see how the bike is balanced a wobble starts in the front wheel and it builds very rapidly. As soon as I hold the bars it disappears. No wobble can be felt in any other condition. Only when bike decelerates in that tempo range and when I let go of the bars. Now you may ask, why do you let go of the bars? I usually don't but none of my other 3 beemers do this. Is this a design issue with the K100RS? Any other ideas? Thanks.
    That is an absolute classic and almost certain result of loose steering head bearings. You should adjust them. Then if you feel any notchiness in the straight ahead position of the steering you should replace them or have them replaced.
    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://web.bigbend.net/~glaves/

  3. #3
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    4,949
    Tire balance or tire wear could also agrivate the situation.





    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  4. #4

    Suspension

    Weak or worn out suspension components could also be a factor here.

  5. #5
    Gravity pockets could be a factor.
    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://web.bigbend.net/~glaves/

  6. #6
    Registered User
    Join Date
    Feb 2018
    Location
    Sturgeon Bay WI
    Posts
    22
    Quote Originally Posted by PGlaves View Post
    Gravity pockets could be a factor.
    You mean gravity pockets in the head bearings?

  7. #7
    Quote Originally Posted by allemande View Post
    You mean gravity pockets in the head bearings?
    I was being factitious.
    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://web.bigbend.net/~glaves/

  8. #8
    Nick Kennedy
    Join Date
    Nov 2011
    Location
    Telluride Colorado
    Posts
    458
    IMHO Sounds like you've got a worn/ wildly out of balance tire.
    This has happened to me several times and new tire always fixed it.
    If you don't want to get a new tire a ounce or two of Dyna Beads in there will fix it.
    Flame suit on!

  9. #9

    Wheels

    I had a bike that would shake at exactly 80mph only. Wheel threw a weight.

  10. #10
    Registered User
    Join Date
    Nov 2009
    Location
    Phila
    Posts
    129

    Head set loose: wobble

    My '85 K100RS has 203,000 miles and I once changed my head bearings. Got the wobble. As I loosened the top triple clamp to fork leg bolts and then snugged the head bearing knurled nut some and re-snug fork clamps, the wobble got less. After several knurled rotations of about 10deg that I did with a giant set of channel lock things the wobble went away. No hand driving has now been possible for 100,000 miles or more. Like Paul Glaves said.

  11. #11
    Registered User
    Join Date
    Dec 2007
    Location
    Indiana
    Posts
    2,524
    I'm with Paul and get it done before you have a real tank slapper event....those are not fun. That can ruin a good pair of underwear.
    MOA #46783

  12. #12
    Registered User
    Join Date
    Feb 2018
    Location
    Sturgeon Bay WI
    Posts
    22

    Steering issue solved on K100RS

    The wobble while decelerating on my 85 K100RS was solved after tightening the steering head bearings. Thanks for the good advice!

  13. #13
    I'm glad to hear it. Usually I say, "Now go ride" but since I don't know how things are where you are I will just say go ride when it make sense to do so.

    I do have to tell a story. When we lived in Kansas the Falling Leaf Rally, sometimes called the Frozen Leaf Rally, was an annual must-go-to. One year a good friend was at the rally on his R100 something. When we got up and everybody was leaving the rally his bike would not start. Ruh Ruh. Ruh Ruh. Pretty soon Ruh. One of the host club members got his pickup truck and jumper cables. Ruh Ruh Ruh. So we decided to push start / bump start the bike. That totally failed to work. At pushing speed the bike front wobbled to the point that he couldn't even keep it in his lane in the campground roadway. Several of us tried to ride it being pushed and it turned into a giggle fest.

    He had said that he noticed a wobble when he accelerated but he just powered up through it. He said he also noticed it slowing down but just used more brake to make it go away

    We finally got it started with jumper cables from the pickup. He had a spare key for the gas tank so rode it from Potosi, Missouri to our house in Lawrence, Kansas without turning it off. The starting issue was a badly worn nose bushing in the starter which caused the armature to drag. The wobble issue was a very loose set of steering head bearings. A few hours in the shop and a new starter drive front bushing and new steering head bearings made the bike east to start and easy to ride once again.
    Last edited by PGlaves; 04-06-2020 at 03:02 AM.
    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://web.bigbend.net/~glaves/

  14. #14
    Registered User
    Join Date
    Nov 2009
    Location
    Phila
    Posts
    129

    Thank you Paul Glaves

    Thanks for helping our K community keep these great bikes running, especially helping the people that recently buy these and need to learn some of the quirks they have to get the great rewards these bikes give.

  15. #15
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    4,949
    Quote Originally Posted by 075038 View Post
    Thanks for helping our K community keep these great bikes running, especially helping the people that recently buy these and need to learn some of the quirks they have to get the great rewards these bikes give.








    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

Similar Threads

  1. another rs handlebar question - 91 k100rs
    By 2slow in forum Flying Brick K-bikes
    Replies: 4
    Last Post: 04-14-2013, 11:47 PM
  2. K75S Handling Question
    By rwat3003 in forum Flying Brick K-bikes
    Replies: 15
    Last Post: 08-25-2010, 08:21 PM
  3. 1100 GS vs. RS Handling Question
    By twobits in forum Oilheads
    Replies: 7
    Last Post: 06-25-2009, 12:11 PM
  4. k100rs handling issues/ bars too small?
    By bill190d in forum Flying Brick K-bikes
    Replies: 9
    Last Post: 05-09-2007, 01:18 PM
  5. K100RS headlight question
    By Mudbug in forum Flying Brick K-bikes
    Replies: 1
    Last Post: 10-24-2004, 05:12 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •