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  • compression test

    Ok so now you find out how inept I am mechanically. Went out yesterday and bought a compression tester. Had the oil filter and drain plugs out with rags stuck in the intake and exhaust ports to keep the bee's etc from nesting in it. Pulled the plugs and put the tester on. Kicked the bike over a few times on each cylinder. Readings were 1&4 -80 psi #2 was 50 and #3 was 42. I'm not a genious but these numbers can't be good. Sat down to contemplate my next move and noticed that any oil that was left in the engine was now in a puddle on the floor and the rags had all been blown out of the ports. Am I correct in assuming that to get the numbers up to the 140 area I'd have to put the filter etc back on and put some oil in this thing? It would seem to me that 2&3 were the ones open during the 18 years of sitting and aren't seating properly? I know that just having it roll over is a good thing but just how bad are these numbers
    mack
    79 XS 1100 SF Special
    HERMES
    original owner
    http://i946.photobucket.com/albums/a...ps6932d5df.jpg

    81 XS 1100 LH MNS
    SPICA
    http://i946.photobucket.com/albums/ad305/mack-055/2.jpg

    78 XS 11E
    IOTA
    https://youtu.be/wB5Jfbp6SUc
    https://youtu.be/RaI3WYHSuWA



    Have recovery trailer and shop if you breakdown in my area.
    Frankford, Ont, Canada
    613-398-6186

  • #2
    You need to have all the ports open for a compression test.
    So take all rags out of intakes and exhaust.That means if you had
    the carbs still on it you would have to hold the throttle wide open to get a
    valid reading.
    Flow is impeded if you have any restrictions on either side of the cylinders.
    HTH.
    Rick
    80 SG XS1100
    14 Victory Cross Country

    Comment


    • #3
      You'll want to pull the plugs out as well for a compression test. You'll need to crank it 4 to 8 times on each cylinder to get a good reading.
      I think I have a loose screw behind the handlebars.

      '79 XS11 Standard, Jardine 4/1, Dyna DC1-1 Coils, 145 mains, 45 pilots, plastic floats - 25.7mm, XV920 fuel valves, inline fuel filters, speed bleeders, Mikes XS pods, spade-type fuse block, fork brace, progressive fork springs/shocks, manual petcocks, 750 FD, Venture cam chain tensioner, SS brake lines

      Comment


      • #4
        If the bike has been sitting for 18 years and it still turns over and has at least some level of compression on all four cylinders I would not at this point take those compression readings too terribly seriously. The piston rings can freeze in their grooves during a long period of inactivity. However, they often will unstick once the engine runs for a while. Get the engine running. If, after you've got 50 or 100 miles on it, the compression readings are low or inconsistent, then I would start to worry about new rings or something. At this point that compression tester is not going to tell you anymore than it already has, even if you do the test correctly.

        Patrick
        The glorious rays of the rising sun exist only to create shadows in which doom may hide.

        XS11F (Incubus, daily rider)
        1969 Yamaha DT1B
        Five other bikes whose names do not begin with "Y"

        Comment


        • #5
          I’d not be overly concerned about compression at this point unless it has a lot of miles or you know it was really abused..
          Put a couple table spoons of oil in each cylinder thru the plug hole, turn the engine over a few times, then clean the carbs and electrical, new oil/filter and start it. They like to smoke a lot for the first five minuets or so. If it runs then do all the regular maintenance for a bike that’s been sitting for a long time. If your going to ride it get some new tires.


          mro

          Comment


          • #6
            Thanx guy's, you made my day. I know it's never been abused and it only has 36000 Km on it.
            mack
            79 XS 1100 SF Special
            HERMES
            original owner
            http://i946.photobucket.com/albums/a...ps6932d5df.jpg

            81 XS 1100 LH MNS
            SPICA
            http://i946.photobucket.com/albums/ad305/mack-055/2.jpg

            78 XS 11E
            IOTA
            https://youtu.be/wB5Jfbp6SUc
            https://youtu.be/RaI3WYHSuWA



            Have recovery trailer and shop if you breakdown in my area.
            Frankford, Ont, Canada
            613-398-6186

            Comment

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