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compression test gauge

Discussion in 'XJ Technical Chat' started by Fongdingo, Dec 28, 2008.

  1. Fongdingo

    Fongdingo Member

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    Okay has any of you all made a gauge for your bike. id like to know all the parts to get and if you did make one would you make it any differently. pic would be helpful to. im asking cause i think i need to check one of my cylinders. the bike don't seem as fast, and since a buddy of mine bought a Kawasaki that he never saw running and boxes full of parts i would like to use it on his too.
     
    Fongdingo, Dec 28, 2008
    #1
  2. Zookie400

    Zookie400 Active Member

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    its around $20 to just buy a compression tester from an auto parts or tool store, just make sure it comes with the right adaptor for your spark plug thread.
     
    Zookie400, Dec 28, 2008
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  3. RickCoMatic

    RickCoMatic Well-Known Member

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    I bought a New one from Sears.
    $25.00
    Very nice tool.
     
    RickCoMatic, Dec 29, 2008
    #3
  4. coolalleycat

    coolalleycat New Member

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    I got one on Ebay for $5.50 a month ago
     
    coolalleycat, Dec 29, 2008
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  5. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Fondingo, your Max has 20K on it. Have the valve clearances ever been checked? If not, I wouldn't bother trying to do compression a test until they have been...
     
    bigfitz52, Dec 29, 2008
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  6. Zookie400

    Zookie400 Active Member

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    EXCELLENT advise!
     
    Zookie400, Dec 29, 2008
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  7. boomer

    boomer Member

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    Whats the proper reading for the compession test? What should the gauge read?
     
    boomer, Dec 29, 2008
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  8. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    According to the factory book for the 550: WARM engine, all plugs removed, full throttle: Max 135psi (9.5KG/cm2) min 100psi (7.0KG/cm2) "standard" 121psi (8.5KG/cm2) As I said these are the specs for the 550 and you don't specify which bike you have. The bigger XJs may be different, I'm giving these to illustrate a point.
    WHICH IS: The exact reading isn't as important as the relationship of the cylinders to each other. Gauges vary, MOTORS vary, so the actual reading is quite a range, for this motor anywhere from 100 to 135psi. What shouldn't vary is the cylinders in relation to each other factory spec is LESS THAN 14psi (1KG/cm2.)
    OUT OF ADJUSTMENT VALVES will throw off compression readings. Factory book also says:
    1. Valve clearance adjustment.
    2. Cam chain.
    3. Air filter, carbs.
    4. Compression test. IN THAT ORDER. (For a reason.)
    If you get a wildly variant cylinder, squirt a teaspoon or two of motor oil in the cylinders and retest.
     
    bigfitz52, Dec 30, 2008
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  9. TheHound

    TheHound Active Member

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    My compression tester has a tappered rubber fitting on it.
    You hold it in the cylinder with your hand.
    Not good for tight places, but on a V8 it works just fine, which is why I originally bought it.
     
    TheHound, Dec 30, 2008
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