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Valve Clearances round 2

Discussion in 'XJ Technical Chat' started by mmcgee, Mar 27, 2013.

  1. mmcgee

    mmcgee Member

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    Okay here are my new measurements with a metric feeler gauge.

    Intake #1 - 0.11 Y260 - In spec
    Intake #2 - 0.15 Y260 - In spec
    Intake #3 - 0.09 Y270 - NEED Y265
    Intake #4 - 0.09 Y270 - NEED Y265

    Exhaust #1 - 0.15 Y260 - NEED Y255
    Exhaust #2 - 0.14 Y260 - NEED Y255
    Exhaust #3 - 0.15 Y260 - NEED Y255
    Exhaust #4 - 0.17 Y260 - In spec

    How does this look?

    Assuming it's going to get tighter, I think I should order extra 255s for intake 1 and exhaust 4.
     
    mmcgee, Mar 27, 2013
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  2. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Ehhh... maybe. Eventually. They have this irritating habit of "bedding in" and settling down to a clearance right on the edge of being tight.

    My '81 has a #1 intake valve that is sitting at .11 and smiling at me and has been for the last three checks. I have a new shim ready; it's not going anywhere.

    Your calculations look fine. Now wasn't that much easier without all the math? .09 minus one size gets you .14, 14 down a size gets you 19, 15 down a size gets you 20. Doing it this way, who needs a chart? Good job.
     
    bigfitz52, Mar 27, 2013
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  3. BruceB

    BruceB Active Member

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    Not to change the post, but I have a question. Can one assume that if a bike had high number shims, IE 280-290 that they might be the original shims? What it be correct that if the clearances go tighter, you would end up with thinner (lower number) shims?
     
    BruceB, Mar 29, 2013
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  4. Bushy

    Bushy Active Member

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    Bruceb ..yes thats been my experience with 3 750 engines that i have checked valve shims on, all of them tight with some in the 280 / 270 sizes, so it must have been a while since they were done. One of them now has a couple of 255 shims. And yep over time you'll be using thinner shims.
     
    Bushy, Mar 29, 2013
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