Revised Valve Specs

Discussion in 'Parallel Universe' started by Emmbeedee, Nov 25, 2012.

  1. Reaver

    Reaver Outta Here

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    F that S!

    In my experience as a Motorrad tech, if there isn't some sort of paperwork that explains it then it's a typo. There are errors all over the tech pubs. During my training I often had to answer wrong in order to get it "Right". Such as....Regarding the f800gs and the f650gs twins, which model has an optional tire pressure monitor?" F650gs which has tubless tires making this possible?? WRONG!! PLEASE TRY ANOTHER ANSWER. Another reason I left.

    Anyway, I believe it did change but I'm not touching anything till I see it in writing and with the applicable SN's.

    YMMV
    #21
  2. JRWooden

    JRWooden Long timer

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    I have sent an inquiry to a helpful insider ....
    If I get anything good back on this I will post.........
    #22
  3. itsatdm

    itsatdm Long timer

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    That is a big jump, but if it on the CD it must be right. I got to go crank in that 1mm clearance for my clutch cable.:deal
    #23
  4. Reaver

    Reaver Outta Here

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    Exactly!

    And I've drained alot of fresh oil after over filling it to "Specification".

    :loco
    #24
  5. vtbob

    vtbob wanderer

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    Just to continue with the idle and un informed (On my part) speculation

    Maybe they changed the material in the valve and they "grow" a bit more with temperature.


    In any case...i'm doing nothing. On my bike when the valves where checked for the first time at 30k miles, there was no adjustment done.

    I have to wonder what the factory settings are!
    #25
  6. Emmbeedee

    Emmbeedee Procrastinators

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    Thanks for this; where did this information come from? Just curious.
    #26
  7. Emmbeedee

    Emmbeedee Procrastinators

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    Just had a look while Jesse, my mechanic, had my cams out to adjust my valves.

    [​IMG]

    Interesting design to the shims. They are tiny, and their size is marked on the side.

    They fit in here:

    [​IMG]

    And when Jesse takes the plastic off, he does it this way, saving time.

    [​IMG]

    This is the shim chart for my bike:

    [​IMG]
    #27
  8. Steveman

    Steveman Been here awhile

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    +1 on newer bikes the clearence decreases, which is a well known problem.
    #28
  9. CaliKarl

    CaliKarl Been here awhile

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    So the new bikes, with bigger clearances, have less power?
    #29
  10. Gangplank

    Gangplank Advenchaintourer

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    Just talked to a shop I trust up in Chico CA. Said the valve specs were changed but recommendation from the shop is to just wait until the next interval and then check and change it if needed. I let him know mine were just done and he said it can still wait until the next needed valve check... Sounds ok to me.
    #30
  11. itsatdm

    itsatdm Long timer

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    I called my dealer today and confirmed the valve lash they are using is what is now the new spec. No indication on their computer how or when this happened. But they will do some research and get back.

    My Haynes manual has the old spec.

    Lose HP? Theoretically yes, but I doubt you will feel it.

    I have a KLX680c that I am constantly experimenting with to get the last bit of HP. I set the intakes at minimum spec and the exhaust at maximum. It did make the bike rev easier and quicker at higher rpm. Less power lower in the rpm range.

    The intakes opens farther and it extends the duration the valve is held open. The exhaust valve stays closed longer on the end of the power stroke. By the time it opens there is less cylinder pressure. I check the valves often to make sure the intakes don't get tight. Something I felt comfortable with on this bike because there are 2 versions of it and that is basically what Kawasaki does with different intake cams on them.

    I won't do that for the BMW because it is a PIA. Next time the valves are done, I probably set them where old and new overlap.
    #31
  12. Emmbeedee

    Emmbeedee Procrastinators

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    Makes sense. My bike needed its checkup so it was logical to do it now, and my wife's 650 had just had its 80K checkup a couple of months ago, but we got a break on the valve check price so it made sense to do hers now too.

    But if either of our bikes had still been in use (ie no snow on the ground) we probably would have waited.
    #32
  13. Gangplank

    Gangplank Advenchaintourer

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    Even better... Just called Sierra BMW here in Reno, the other BMW shop I trust. That is the shop that checked mine in Aug. The service department called me back already and they kept my valve specs from when they checked them in Aug. sounds like I should be good for now. only 2 of the intake valves were .02 tight (measured .20). The rest of the intake and exhaust clearances were within the new specs. Great service!
    #33
  14. NCD

    NCD Dirty Hairy

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    Having just checked mine, it will be 2 years before I'm back in there. I'm going to leave them be. The collective of 800 motors have bajillions of miles on them at the old specs, and we've all been riding around blissfully unaware of the change. Hell, the specs could change again before I open it up again!

    I will admit that its a little creepy riding it knowing they hhave changed. If they would just tell us why.....
    #34
  15. Reaver

    Reaver Outta Here

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    It's on a "need to know" basis and you're just a customer! :rofl
    #35
  16. ebrabaek

    ebrabaek Long timer

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    No. For you to notice a performance difference... The motor would sound like it's about to grenade.
    #36
  17. Steveman

    Steveman Been here awhile

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    +1 ! :1drink
    #37
  18. CaliKarl

    CaliKarl Been here awhile

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    Okay. So why then not keep the clearances loose in the first place? So that they're ringing the dinner bell?
    #38
  19. ebrabaek

    ebrabaek Long timer

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    It does not make any sense. The other bikes I have all have their valves in the .08-0.22 on the intake side, and 0.18-0.32 on the exhaust side. The next biggest bike is my 55 RWHP Suzuki DRZ 470. A full flood race build motor with just about twice the output as compared to stock. it runs 0.10-0.20 intake, and 0.20-0.30 exhaust. The 8GS changed in two ways. space is moved up, and margin was increased from 0.08 to 0.11 ( exhaust). That margin is pretty standard, as the other bikes I have are 0.10. But as to determine why BMW did this.... My guess is some idiot thought this would be a good thing. That's it. They have prided them self that these valves do not move, thus it is unnecessary to increase the spec's. Mind you as abrasive air is ingested through normal operation ( slightly increased with guaze filters like K&N) over time the valve seat will wear, and the valves will now sit a little higher in their seat, thus decreasing the clearance between shim, and the valve rod. But to increase the tolerances like this is sort of like giving your Yugo a rear defroster to keep your hands warm, when you push it..... except our BMW does not break down like the Yugo.....wait... What did I just say...:D:lol3. IMHO... The old valve specs are plenty. You most likely will not hear any difference in the sound if you change to the new spec's. You would just be wasting your time. This is my opinion only. If this bike had a tendency to move valves... I'd say great, change the spec's to facilitate this, but it does not. Don't sweat it, and just check'em at next scheduled time.:freaky
    #39
  20. Reaver

    Reaver Outta Here

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    So I'm at the Dealer yesterday paying too much for parts when I asked the mech for proof of change, Memo, Service instruction whatever. They have the time now and he did look but found nothing. Having bought 3 bikes there recently I trust they would provide me with it if they could.

    Ignorance is bliss. I did not read this thread. I did not read this thread. I did not read this thread.
    #40