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Thread: ‘90 K75S…Fork oil leak from pinch bolt?

  1. #1

    ‘90 K75S…Fork oil leak from pinch bolt?

    The other day I noticed about a quarter teaspoon of fork oil on the right side rotor and wheel directly under the fork tube. It seemed to be coming from one of the pinch bolts. Thought that was weird… so I cleaned it up and took it for a short ride. The next day I saw same evidence. It doesn’t seem like it’s coming from the drain bolt and I saw no evidence of it leaking higher up on the fork tube. Is it even possible for a leak to come from around one of the pinch bolts?
    1990 K75s, 2001 R1100RT

  2. #2
    3 Red Bricks
    Join Date
    Jan 2007
    Pleasanton, Ca.

    If you want to prove that, take that pinch bolt out, clean the fork an go for another ride with the bolt removed. I’m pretty sure it will end up just like what you have now.

    Easiest way to find the source of a hard to find leak is to THOROUGHLY clean the entire area. Then dust the area with a powder like baby powder or spray deodorant powder. Then go for a short ride until you start seeing a streak in the powder. The streak will point to the source of the leak. It won’t be the pinchbolt, that’s just the low spot that the oil is running to.

    Last edited by 98lee; 03-23-2022 at 05:29 AM.

    Ride Safe, Ride Far, Ride Often

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

  3. #3
    Could be that the oil is coming from the bolt that secures the fork internals to the lower fork leg. It is installed from the bottom and is accessed once the axle and wheel are removed. There should be a copper crush washer on the bolt. This kind of leak is not very common in my opinion but would explain where the oil is coming from. Probably best to remove the fork from the bike to fix if this is the problem.

    '17 R1200RS, '03 R1100S BCR#6/200, '85 K100/1100RS, '16 R1200RS (gone) '11 R1200RT (gone) '05 R1200ST (gone) '99 R1100S (gone) '96 Ducati 900SS/SP (gone) '92 K100RS (gone) 500,000+ BMW miles

  4. #4
    Thanks guys, I appreciate the recommendations. Will post back when I have an update!
    1990 K75s, 2001 R1100RT

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