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How to Disable TCI for Compression Check?

Discussion in 'XJ Technical Chat' started by cdnjj, Mar 16, 2021.

  1. cdnjj

    cdnjj Member

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    I read elsewhere it is good practice to disable the TCI for a compression test. Makes sense as it removes chance of arcing.

    How do I do this properly ? Is it just a matter of removing the 3 main connectors?

    460EBB81-ED0B-4E05-9CB8-177D1BF2AAA2.jpeg
     
    cdnjj, Mar 16, 2021
    #1
  2. Franz

    Franz Well-Known Member

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    Yes remove the connector blocks from your TCI unit.
     
    Franz, Mar 16, 2021
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  3. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Note that the TCI (box with the green label in your photo) only has two connecters. Unplug both.
     
    k-moe, Mar 16, 2021
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  4. cdnjj

    cdnjj Member

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    Thank you for the guidance. 120psi +/- 2 on a cold engine across all 4 which I think is ok.
     
    cdnjj, Mar 16, 2021
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  5. XJ550H

    XJ550H Well-Known Member Premium Member

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    good enough to run will likely increase once you get it running
    have you checcked valve shim clearances?
    XJ650 and XJ750 air-cooled engines:
    Minimum: 128 psi
    Standard: 156 psi
    Maximum: 171 psi
    Max. variance between lowest and highest: 14 psi
     
    XJ550H, Mar 16, 2021
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  6. Yammaat

    Yammaat Active Member

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    You could measure again with some oil on the pistons.
    Could make quite a difference.
     
    Yammaat, Mar 17, 2021
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