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Thread: 86 K75C valve adjustment questions

  1. #1
    Registered User jad01's Avatar
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    86 K75C valve adjustment questions

    I am doing my first valve adjustments on my K75C (currently about 53K miles; I don't know if/when the valves may have been checked/adjusted prior to my ownership) and have a couple of observations and questions:

    -This is my first time doing an adjustment on this bike (or any with a shim/bucket arrangement). I'm using both a Climber and Haynes manual to guide me. I have the special BMW tools to do the adjustment and an assortment of shims. I found that the exhaust valves were all tight (0.006 inches relative to the specification of 0.010-0.012 inches). The #3 cylinder intake valve is also slightly tight (0.005 inches relative to the spec of 0.006- 0.008 inches). The #1 and #2 cylinders are at 0.006 inches. I had the shims to get the exhaust valves all to 0.011 inches (I completed those adjustments yesterday), and I think I have the shim to get the #3 intake valve within spec. My question is should I also adjust the #1 & 2 intake valves since they are on the low end of the specification?

    - When I pulled the valve cover gasket (rubber seal) off, there was a black film left behind on the head in each corner (see photos). Should I remove it or leave it in place when I put the gasket and cover back on? Is it some sort of silicone adhesive to "locate" the gasket correctly before placing the gasket and cover back on the head?

    - Any other advice is welcome before I button this back up...
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    Last edited by jad01; 12-03-2019 at 03:29 AM.
    Jim (MOA 83200)
    '78 R80/7 (Anastasia) and '84 R100RS (The Millennium Falcon), '86 K75C (Icy Hot)
    '90 and '93 Mazda Miatas (Jelly Bean and Red Hot), '97 Nissan XE PU (Mighty Mouse)
    '96 Giant Upland (big Kendas, baby!)

  2. #2
    It is optional whether you adjust those 2 intake valves. They are usually so stable that they are unlikely to get out of spec any time soon.

    That sealant is placed where there is a seam between two parts that the valve cover seals against. A light smear of Permatex Ultra Gray or similar would be my choice, right on top of what is there.
    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
    Registered User drneo66's Avatar
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    Chris Harris has a nice video that walks you through each step.

    Personally I always removed the previous corner gasket material with a paper towel or soft plastic scraper (old library card), but if Paul says it's okay, then you'll be fine

    I also put a thin piece of wood under the clutch-side of the center stand while putting the cover back on. This prevents any remaining oil from running over the lip and into your gasket sealer or rubber gasket.
    Current: 2007 BMW R1200RT, 2013 F800GS
    Former: 1995 BMW K75S, 2009 BMW G650GS
    MOA Member #:150400, IBA#: 37558

  4. #4
    Registered User jad01's Avatar
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    Quote Originally Posted by PGlaves View Post
    It is optional whether you adjust those 2 intake valves. They are usually so stable that they are unlikely to get out of spec any time soon.

    That sealant is placed where there is a seam between two parts that the valve cover seals against. A light smear of Permatex Ultra Gray or similar would be my choice, right on top of what is there.
    Ok, thank you- I appreciate your insight! I have some Three Bond in the cabinet (better than Two Bond, I think...); maybe I can try that (?) or I'll head up to the parts store for some Permatex.

    Quote Originally Posted by drneo66 View Post
    Chris Harris has a nice video that walks you through each step.

    Personally I always removed the previous corner gasket material with a paper towel or soft plastic scraper (old library card), but if Paul says it's okay, then you'll be fine

    I also put a thin piece of wood under the clutch-side of the center stand while putting the cover back on. This prevents any remaining oil from running over the lip and into your gasket sealer or rubber gasket.
    Thank you! The video was helpful and I appreciate the tip about the shim under the center stand!

    Thank you both!
    Jim (MOA 83200)
    '78 R80/7 (Anastasia) and '84 R100RS (The Millennium Falcon), '86 K75C (Icy Hot)
    '90 and '93 Mazda Miatas (Jelly Bean and Red Hot), '97 Nissan XE PU (Mighty Mouse)
    '96 Giant Upland (big Kendas, baby!)

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