Did I mortally wound my motor? Previous tune up valve clearances set to tight.

Discussion in 'GS Boxers' started by Poway, May 5, 2012.

  1. Poway

    Poway SHED (Shit Head)

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    Hi ADV,
    Despite having JVB's DVD, 2 manuals and tons of internet info, I blew it. On previous tune up (6000 miles ago) I set my valve clearances to tight, and probably not on TDC. Mistake caught on my current tune up. At TDC (verified) I can not get minimum clearances on my both intake and exhaust, left side valves. At full extraction all 4 valve springs, have almost no clearance. Approx 1/5 the recommended. The right side of the motor is OK. Bike was running great.
    Spoke to dealer about it, he said mistake is unreversable. And that things will get worse. then bad. Much better to err on the loose side than tight on valve clearance settings.
    1999 GS1100
    How bad did I screw up? Did I cause the beginning of the end?
    Thanks in advance
    #1
  2. mousitsas

    mousitsas Long timer

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    tappet valves get looser with time, shim valves get tighter. Yours are tappets.
    #2
  3. Jim Moore

    Jim Moore Long timer

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    You know you have to turn the motor 360 degress before you check the other side, right?
    #3
  4. Beezer

    Beezer Long timer

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    ya... make sure the procedure is done correctly.

    if it was done improperly... are there any issues with how the bike runs?

    if you are doing the procedure correctly now and there is clearance problems I would do a leak down check to see if the valves are burnt. this would only be the exhaust side. If it's cooked then time for valve work.
    #4
  5. Anorak

    Anorak Woolf Barnato

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    As long as you had some clearance, don't worry about it. The danger is if the adjustment is so tight that the valve stays open some amount and the high temperature combustion products erode an erosion in the valve head. Too tight valves will cause starting difficulty if they're tight enough to do damage.
    #5
  6. Poway

    Poway SHED (Shit Head)

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    Jim I did not rotate the engine 360. After your post, I rotated and all is well!!!
    Thank you
    #6
  7. tagesk

    tagesk Tuscan rider

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    Sir,
    That is contrary to everything I have heard and experienced.

    As far as I know, the valves are harder than the cylinder head.
    And they work themselves upwards, slowly but surely.
    The gap above them gets smaller.

    This corresponds to my 190.000 km of experience with the R-engines.
    The gap gets smaller, and must be adjusted.

    Can someone correct me if I am wrong, please!

    [TaSK]
    #7
  8. tagesk

    tagesk Tuscan rider

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    Sir,
    I will take the liberty of adding this to the GSpot FAQ.
    If you don't mind!

    [TaSK]
    #8
  9. tkent02

    tkent02 Long timer

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    You think the dealer was just trying to sell you an unneeded replacement engine?
    I bet they would have sold your old engine on to the next guy that needed one.
    #9
  10. Gezerbike

    Gezerbike Hey Rocky...........

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    You are correct. :nod And I for one always make sure mine are looser than tighter when setting them.
    #10
  11. marty hill

    marty hill The Energizer Bunny

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    Always err on the loose side! :deal
    #11
  12. Jim Moore

    Jim Moore Long timer

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    Atta boy! Next time, when you get to tdc wiggle the rocker arms on both sides. One side will be loose. That's the side to start on.
    #12
  13. marty hill

    marty hill The Energizer Bunny

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    Great catch Jim!:D
    #13
  14. bajaburro

    bajaburro Ancient Adventurer

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    loose valves,loose women,good.got that now?
    #14
  15. vagueout

    vagueout Long timer

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    Likely no harm done, a compression check to compare left to right should answer the question.:*sip*
    #15
  16. MrPulldown

    MrPulldown Long timer

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    I can go both ways. The vavles will sink into the head (tighter). But the tappets will wear too (looser). Everyones and engines experiance is different. Becuase of this some swear that as the engine wears the vavles get tighter or looser. On a well designed engine, the two happen at the same rate, and you never need to adjsut your vavles. Like on my DR.:evil
    #16
  17. Chat Lunatique

    Chat Lunatique ACK

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    See post #16

    What you say is true BUT.....it is not only the reduction in valve clearance due to the valve settling in the valve seat that must be compensated for. The cam follower also wears thereby INCREASING the valve clearance. If you take off your cam follower to adjust the valve shim, you will notice wear on the surface that contacts the cam lobe.
    #17
  18. Lenz1

    Lenz1 Been here awhile

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    The wear at the valve head / cylinder seat(A), wear at valve stem tip / tappet(B), wear at the cam / shim / follower(C) all factor into equation.

    Wear at A closes the valve train clearance, wear at B opens the valve train clearance and wear at C opens the valve train clearance also. Adjustment at C is sorta idiot proof - if you can access / use high precision feeler gauges and deal with removal / replacement of shims.
    #18
  19. tagesk

    tagesk Tuscan rider

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    So we understand that, in theory, the gap can become both smaller and bigger.
    Depending on where the wear is.

    In reality and as a general advice, assuming without exception the BMW R-engine before the cam-head, consensus seems to be that the gap gets smaller.
    And, because of that (it gets smaller and not bigger), it is a maintenance issue that should not be skipped.

    (Please do read from the above that any comment relating to shims, to theory, to one-in-a-lifetime experiences, to other engines, to older or newer designs, earthquakes, to aircrafts, to fine wine or attractive women, while mostly interesting, are not relevant in this context)

    In addition, we accept from one of our Mechanics in Residence that as a general observation, if you adjust the clearance so wrong that it might hurt the engine, you will have a very hard time starting it. Or, in other words: If you pay attention you will notice something is wrong and even badly out of spec valves will not, as a general observation, harm the engine.

    I will add all this to the GSPot FAQ in one form or another.

    To the thread starter: Sorry to have hijacked your thread!

    [TaSK]
    #19
  20. diabolik37

    diabolik37 Push Dumb C***

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    Are you saying that if you turn your engine 360 degrees, your engine actually stop in a differente location? :huh
    #20