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Thread: Smoother ride on 91 K75S?

  1. #16
    For perspective, I had a 1986 K75T - a K75C with a windshield but not the C fairing, a double bucket seat, and bags. It had the long travel forks. I did not like the cushy, deep dive forks. In 1987 when the K75S appeared I ordered all of the "S" fork innerds and converted the OEM forks to the "S" forks. The difference was amazing, and to my liking.
    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/

  2. #17
    Quote Originally Posted by jconway607 View Post
    Lee,
    I understand that the K75S models were, I suppose, sold back in the day to people wanting a "sporting" suspension for the "twisties". But really, anyone like myself who is riding a 30 year old motorcycle is probably more interested in a comfortable ride that dragging the pegs all day. Comfort is my goal these days. I would like just a bit more on this bike.
    The K75S forks should not be harsh. That spring set has a soft spring for slight bumps and a stiffer spring for real shocks. It cuts the dive but still cushions the lesser bumps. If you have harshness that implies stiction.

    A careful alignment of the forks is in order. The usual culprit is at the axle, but an issues is possible at the fork brace. I do it with the springs removed and slide the sliders up and down by hand to ensure the brace is correct and the axle is correct.
    Last edited by PGlaves; 07-21-2021 at 07:07 PM.
    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. #18
    JohnWC
    Join Date
    Mar 2010
    Location
    Akron, Ohio
    Posts
    726
    Lee,
    I'm seeing a lot of forks on Ebay that claim they are from a C model. But, many of them have the large, balloon stile dust cover at the top of the slider. I thought that only the S forks had that style cover. Can the early (say pre-89 bikes?) with the C forks have that large style of dust cover? I'm not sure that people who are selling these know there is a difference in forks, and if I decide to change mine, I don't want to just put another set of S forks on. Thanks.

  4. #19
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    5,221
    John,

    The early pre-Showa (pre 9/91) forks were all made by Fichtel-Sachs (both C and Sport). They use the same 41.4 tubes and the same sliders. All F-S forks have the bulbous dust boots. They are the same on the outside, just completely different internals. The C forks will work with your triple clamps.


    HOWEVER, I still don't think that is your problem. I believe that you have damaged or binding forks. My bikes move a couple inches when pushing on the bars at a stop with the front brakes locked. The S forks SHOULD not be harsh. Just for the better handling and less dive at a stop, I would recommend finding the problem and fixing it rather than swapping forks. There are several internal parts that could be worn or damaged or the forks could be bent or misaligned.

    What did you ever do about the rear shock?



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  5. #20
    JohnWC
    Join Date
    Mar 2010
    Location
    Akron, Ohio
    Posts
    726
    Lee,
    Thank you for the quick reply to my question. Sorry to keep asking for answers, but I trust your knowledge base.
    I've taken a few shorter rides on the bike at this point, about 15 miles each. I'd have to say that the fork action is really not harsh. In fact when I do the same thing you suggest, locking the front brake and rocking the front, mine does go up and down a few inches also. And coming to a stop, the front doesn't dive much, just slightly. Maybe it's working like it should. Wish I knew someone around here with a k75 to compare it with. I wouldn't mind a bit more movement over slight bumps, but like someone said, it's not going to perform like my oilhead did. Maybe I'm being too sensitive.

    Due to the movement of the sliders when I rock it, I didn't think the forks were bent. But I could be wrong. I would like to test them, but I assume that to do that I would need to separate the wheel, fenders, etc. and then take all the parts out of the tube so the sliders could mover freely. Is that right or is there an easier way to do the slider test?

    I did reset the rear shock to the firmest setting before taking it out. It was a firmer ride. I don't know if I noticed a difference with the front's performance, but overall it seemed good.

    Thanks again for the help, Lee.

  6. #21
    Quote Originally Posted by jconway607 View Post
    Lee,
    Thank you for the quick reply to my question. Sorry to keep asking for answers, but I trust your knowledge base.
    I've taken a few shorter rides on the bike at this point, about 15 miles each. I'd have to say that the fork action is really not harsh. In fact when I do the same thing you suggest, locking the front brake and rocking the front, mine does go up and down a few inches also. And coming to a stop, the front doesn't dive much, just slightly. Maybe it's working like it should. Wish I knew someone around here with a k75 to compare it with. I wouldn't mind a bit more movement over slight bumps, but like someone said, it's not going to perform like my oilhead did. Maybe I'm being too sensitive.

    Due to the movement of the sliders when I rock it, I didn't think the forks were bent. But I could be wrong. I would like to test them, but I assume that to do that I would need to separate the wheel, fenders, etc. and then take all the parts out of the tube so the sliders could mover freely. Is that right or is there an easier way to do the slider test?

    I did reset the rear shock to the firmest setting before taking it out. It was a firmer ride. I don't know if I noticed a difference with the front's performance, but overall it seemed good.

    Thanks again for the help, Lee.
    If it hasn't already been done drain the fork oil. Then install new fork oil precisely to the volume specified for each leg. If perchance there is as little as 10cc more oil than specified it will reduce dive. On several bikes I have added fork oil to reduce the air column which then compresses faster.

    Also, it is possible an owner has installed a longer than stock preload spacer. Make sure that is stock too.
    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/

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