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Thread: 1994 K75 valve adjust needed?

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  1. #1
    Registered User wjg4oh's Avatar
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    1994 K75 valve adjust needed?

    My '94 K75 has 22,000 miles on it. I checked the valves for the first time last week and the intake valves were all nicely within spec, but all three exhaust valves were over .30 mm. I was surprised given the low miles on the bike, and thought maybe some carbon had fallen down between the valves and seats so I buttoned everything up and took it for several rides.

    Today I checked them again and confirmed my earlier measurements:
    #1 exhaust (front) .37
    #2 exhaust .33
    #3 exhaust .32

    I'm assuming they need adjustment, but I've also heard it's ok if the exhaust valves are a little loose since they tend to close up over time, but .37 seems like a lot.

    The bike is running fine.

    Suggestions?
    Wally Gingerich
    Shaker Heights, OH

  2. #2
    BMW uber alles! Zagando's Avatar
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    Go for it!

    Funny; I also have a 94 K75S with 27,000 miles (turned over to 27k 4 miles before arriving at the dealer's).

    I thought one of the valves was a bit off and sure enough, it was (but not by as much as yours). I had them adjust and re-shim all three cylinders as well as put in a new set of plugs for good measure.

    My goodness gracious what a difference it made! The bike is smoother than ever before. Now I just need to get the throttle bodies synched at some point and it'll be smooth all the way to redline.
    ---Jeff

    ex: K75S Berlina R100GS/PD , K100RS , R75/5 , R60/2

  3. #3
    3 Red Bricks
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    There are two possibilities:

    Someone adjusted the valves incorrectly previously.

    You used too much pressure in pushing the feeler gauge and came up with an inaccurate measurement.

    I have no way of knowing which.




    After any change of valve adjustment it is recommended to rebalance the throttle bodies.



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  4. #4
    Registered User wjg4oh's Avatar
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    I bought the bike at 10,000 miles. I suppose the PO could have adjusted the valves, but I rather doubt it.

    I try to be careful not to use too much force on the feeler gauges -- when I feel a light drag I assume that is the correct measurement. It's difficult to get an accurate reading, however, as I have to bow the guages to get them into the gap, and when bowing them I may be using too much force.

    Is it possible the valves came like this from the factory, or opened up this much?

    I'm thinking of adjusting #1 to bring it in line with #2 and #3.
    Wally Gingerich
    Shaker Heights, OH

  5. #5
    3 Red Bricks
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    Wally,


    It sounds like you might be trying to insert the feeler gauge on the intakes from the top and the exhausts from the bottom.

    If you insert the gauge into the intakes from the bottom (from the spark plug side of the cam) and the exhausts from the top (from the spark plug side of the cam) you shouldn't have to bow the gauge.


    Sure, it's possible that they were misadjusted at the factory or at the dealer first service. It is also possible that the wrong oil was used, especially during break-in (which your bike hasn't finished doing). These bikes require oils that are high in anti wear additives SG and earlier. The antiwear additives were removed from most subsequent grades of oils as they mess with the catalytic converters in cars. It is very common in older flat tappet cam engines for the cam to wear rapidly after a new cam replacement if the correct oil with the high antiwear additives isn't used.


    If you are SURE that your measurements are correct, I would correct all that are not within spec.. The .33 would adjust to .28 and the .37 would adjust to .27. Make sure the new shims are well seated, then crank the motor over several times, then measure
    them again. Write down the results of all the valves for your records and date it. Check them again next year. See if they've moved, especially the one that started at .37.




    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

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

  6. #6
    Registered User wjg4oh's Avatar
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    Thanks for the suggestions, 98lee.

    I measured the valve clearances very carefully this afternoon (third time!) using the go-no-go technique and this is what I found:

    #1 .356mm, .014"
    #2 .330mm, .013"
    #3 .305mm, .012"

    I got the necessary shims and adjusted #1 and #2 -- and now all three exhaust valves are nicely in spec.

    I checked the air bypass screws this evening prior to doing a TB sync tomorrow and found that #1 was 3 turns out, #2 was 2.5 turns out, and #3 was just a tad over 1 turn out. Sure looks like a PO had to compensate for mis-adjusted valves. They must have gotten mixed up (easy to do) when adjusting the valves and put in smaller rather than larger shims -- guess they didn't check their work!
    Wally Gingerich
    Shaker Heights, OH

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