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Thread: '94 K75S rude awakening and top box mounting question

  1. #1

    '94 K75S rude awakening and top box mounting question

    Hello! I recently acquired a beautiful '94 K75S with only about 24K miles on it. This was a move to simplify my life and get down to one bike that I could tinker on and also rely on to get me around. I love the way it rides - in fact I love just about everything about it except one. I bought the bike about 900 miles from home and rode it back. It was about 100F the whole way home. It did great, but after I got home I changed the oil and noticed very minor oil leaks from, well, just about every seal on the bike's engine... It looks like it will need pretty much every seal and gasket on it replaced (except the head gasket....). So much for simplifying my life!

    Anyway, aside from fishing for sympathy, the real reason I am writing is to see if I could get some advice on mounting the stock top box on my bike. I have a OEM rack and top box along with all the screws and washers that go with them. I do not have instructions though.

    From what I picked-up off the internet, the rear cowl should be marked on the inside for where the holes need to be drilled (true? If so, what size holes?). I can't believe that the rack simply mounts to the cowl plastic directly. Isn't there some sort of sub-frame that the rack mounts to? IF anyone has an old set of directions sitting around or knows the steps, I would be very appreciative!

    PS - one thing I do not have is the "foil" that goes between the rack and cowl. From what I understand this is like the clear protective film that they put on the front of cars. Is this something I need to worry about?

    Thanks again,
    Kikemon/Mitch

  2. #2
    When you look at the plastic tail cone where to drill is obvious because each location is significantly reinforced. Pick a drill bit as small as possible that will still allow the bolt to go through the hole. You need to have the tail cone off the bike to do this the easy way.
    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
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    Mitch,

    Welcome to the forum and congratulations on buying a great bike!


    There are dimples on the underside of the tail section that locate the holes, like Paul said.

    The holes are NOT to be drilled perpendicular to the top surface! They are suposed to be drilled perpendicular to the bottom edge of the painted part of the tail section (not the black part).

    If you have a drill press and 2 levels it'll make it easier. Level front to back and side to side. Having an assistant to hold the part and the levels while you drill the hole really helps. Put cardboard on the table so you don't scratch the top of the tail section. Take your time and try to be as precise as possible.

    Start with a drill smaller (about 75%) than the bolt size.

    Put painters tape in the area where the drill will come through to prevent the paint from chipping. Back way off on the feed rate just before the drill starts to break through, or it will really bite in.

    If the holes don't perfectly line up, see if you can get at least two or three bolts in, then start angleing with a hand drill or enlarge the hole one size at a time with number drills until it fits.

    Don't forget the rubber washers between the rack and the paint. I have never seen any foil on any K75 with a rear rack. No reinforcing needed as the rear case is only rated for 11 pounds.


    As far as your leaks, DO NOT TIGHTEN YOUR VALVE COVER OR CRANK COVER BOLTS TIGHTER THAN 7 ft/lb.!!! (84 in/lb) You wil end up stripping the threads out of the cam journals.

    I gotta go now, but I'll be back Monday to tell you how to take care of your leaks.

    And I'll see if I can post some pictures of the tail section holes.





    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  4. #4
    When you buy an old low mileage great looking bike, oil leaking from every seal should be an expectation. In addition to seals drying up, old grease turns to mush. Regreasable bearings (headstock and pivots) need to be regreased and sealed bearings (front wheel) need to be replaced. Electrical connectors need to be disconnected, de-oxidized, and reinstalled. Anything made of rubber (hoses, belts, tires, tire valves, dampers) is suspect until proven roadworthy.

    A 25 year old bike does not start out simple unless someone else has already done the work, and done it correctly. But once rectified it can be an excellent companion.
    Lee A. Dickinson - Danielsville, GA USA
    Airheads #3480 | Iron Butt Assn. #8914
    1976 R75/6 - 1992 R100RS - 1993 K1100RS - 2013 R1200GS

  5. #5
    Thanks all for the info and great advice. I am hoping I can work through the issues slowly and continue riding the bike between projects. I am a little unclear on the orientation of the holes (not the location but the direction they go in) for the rack, but I'll re-read this thread when I get it apart and see if I can figure it out.

    - Mitch

  6. #6
    3 Red Bricks
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    Mitch,

    I'll post pictures of the hole orientation tomorrow. As for now, I'm off to the 153rd annual Scottish Games.




    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  7. #7
    3 Red Bricks
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    Mitch,



    On the inside of the tail section there are four bosses for the tail rack bolts. There is a dimple in each one that is where the bolt hole should be centered.
    P1020002.jpg

    If you look at your rack, the bolts do not go in perpendicular to the rack.
    P1010991.jpg

    I was mistaken (been a few years since I did my last one) when I said that the bolt holes were perpendicular with the lower edge of the tail section. They are not. The ONLY reference surface is the face of the bosses. The bolt holes should be perpendicular to the face of the bosses.
    P1010996.jpg


    P1010995.jpg

    To make keeping the holes at the correct angle easier, take a sheet of plywood and attach a block 6 1/2" tall to one end. Preferably the block should be a bit wider than the two holes at the front end of the tail section (7 1/4" to 8"). Block in picture is not the correct dimension.
    P1010998.jpg

    Lay tail section upside down on plywood and block. Lightly screw tail section to block with two screws. You can now take this to a drill press and get all 4 holes the exact same angle. DON'T FORGET TO USE painters tape or masking tape on the back side of where you are going to drill the holes to prevent paint chipping. Use a 15/64" drill.
    P1020001.jpg
    Last edited by 98lee; 09-05-2018 at 04:44 PM.
    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  8. #8
    Registered User drneo66's Avatar
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    Congrats on the new bike! The "S" models are the best

    If you're not comfortable drilling the tail section, there are plenty of relatively cheap options on ebay... (depending on your bike's color).
    1995 BMW K75s - 100k and climbing!
    2007 BMW R1200RT - 62k
    2009 BMW G650GS - 22k and ready for Alaska!

  9. #9
    3 Red Bricks
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    Since we were talking about this, I decided to make a cleaner, more permanent version of the fixture for future use.

    P1020003.jpg

    Screwing the tailsection to the riser block (6 1/2" tall) makes holding the tail section easier. But remember to hold the rear of the tail section down as you are drilling in case the drill bites into the plastic.
    P1020004.jpg

    The fixture and a drill press make this an easy one person job.
    P1020006.jpg

    The fixture insures that all holes will be at the same correct angle. If holes do not perfectly align with rack, slightly enlarge one hole at a time until all four bolts fit.
    P1020005.jpg

    USE BLUE PAINTERS TAPE ON THE BACK SIDE (the side the rack goes on) WHILE DRILLING THE HOLES TO MINIMIZE PAINT CHIPPING FROM THE DRILL COMING THROUGH!
    Last edited by 98lee; 09-05-2018 at 05:30 PM.
    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  10. #10
    Registered User drneo66's Avatar
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    Quote Originally Posted by 98lee View Post
    Since we were talking about this, I decided to make a cleaner, more permanent version of the fixture for future use.
    I love it! For the OP, now you just box up the tailbox, send it to Lee with some beer/coffee money and have him send it back.
    1995 BMW K75s - 100k and climbing!
    2007 BMW R1200RT - 62k
    2009 BMW G650GS - 22k and ready for Alaska!

  11. #11
    Quote Originally Posted by drneo66 View Post
    I love it! For the OP, now you just box up the tailbox, send it to Lee with some beer/coffee money and have him send it back.
    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/

  12. #12
    3 Red Bricks
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    Quote Originally Posted by drneo66 View Post
    I love it! For the OP, now you just box up the tailbox, send it to Lee with some beer/coffee money and have him send it back.
    If he's in NorCal, he's welcome to bring it by.






    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  13. #13
    You guys are fantastic! Thank you so much for the great tutorial!

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