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Thread: Does this valve look ok to you?

  1. #1
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    Does this valve look ok to you?

    So I had a melt down in my r69s, lean carb + advanced timing + who knows what. Got the new pistons from vech, bores done, so I'm looking at top end stuff now. The chamber looks ok, scraped a little melted piston from the inside, but it should be ok. I'm going to pit some pics, so if you all think things are toast, let me know. Thanks!
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  2. #2
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    The other valve

    Here's the other valve.

  3. #3
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    Forgot the pic

    Here it is
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  4. #4
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    And the head itself

    Cleaned up just a little...
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  5. #5
    Benchwrenching PGlaves's Avatar
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    Can't tell.

    Look straight at the side of the head of the valve and measure the margin (width of the edge). I don't know the spec but it ought to be a clean square edge.

    Then, look at that exhaust seat. I note the intake remains shiny as expected but the exhust seat appears to be a little knarly but I can't tell for sure.
    Paul Glaves - "Big Bend", Texas U.S.A
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  6. #6
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    Here's a better pic of the exhaust valve seat

    Here's a better pic from a "real" camera of the valve seat.
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  7. #7
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    Better pic of the valves

    I'm mostly concerned about the crap below the valve guide area and above the seat on both valves. I'm assuming that it could come off fairly easily, but it may require a little "persuasion". As long as it's below the valve guide, should there be a problem?
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  8. #8
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    Same Q, different valve

    Thanks!
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  9. #9
    Cam Killer marchyman's Avatar
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    Were it my bike I'd at a minimum lap the valves to the seats. Depending upon the results the seats may need to be re-cut and the valve re-ground.

  10. #10
    Benchwrenching PGlaves's Avatar
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    Quote Originally Posted by marchyman View Post
    Were it my bike I'd at a minimum lap the valves to the seats. Depending upon the results the seats may need to be re-cut and the valve re-ground.
    I agree. Post#6 clearly shows some seat erosion at the 6:00 to 7:00 position in the photo but post#7 shows what appears to be plenty of margin on the valve.

    Deposits on the stem should not be a problem provided they are below the guide.
    Paul Glaves - "Big Bend", Texas U.S.A
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  11. #11
    Registered User vechbmw's Avatar
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    RE: Does this valve look good to you?

    Looks are not really that much of a consideration. You have to do some measuring and examination here.
    1. if you mount these valves in a valve grinder, or a lathe, by the stems, and turn them slowly, does the face of the valve turn true? Lots of heat can warp a valve. If they are warped, replace them. Forget grinding them. New ones are not that expensive.
    2. Due to the lack of lead in gas, the valves all wear on the stem, where they run in the guide.
    If the valve passes the test described in #1 above, measure the stems, in various places, down the length. Is it consistent? If not, replace them. How does it fit the guide? Is it time for new guides?

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