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    Compression troubleshooting

    Did a compression test today got 150 PSI +- 3 PSI on both cylinders after adding oil to the cylinder got 7 PSI higher. Am I looking at piston/rings issues or valve issues?

    #2
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      #3
      20,000 mi by the way

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        #4
        Is there a problem you're trying to diagnose?

        I don't know what it should be, but that sounds about normal.
        1988 Hawk
        1989 Hawk
        1998 ST1100
        1999 ST1100
        North Georgia

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          #5
          Bought a compression tester to try and be a responsible bike owner LOL So now I'm chasing this goose.....anyway I have found online says about 200 is perfect.

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            #6
            Nothing will perfect. Unless it's right after a completed rebuild in a brand new engine. I looked around for a few minutes. 192 psi. With a tolerance of 28. So 150 isn't far off.

            Search here and you'll find instructions. Other people with similar results. So I wouldn't work about it.

            Ride it more and worry about it less.
            1988 Hawk
            1989 Hawk
            1998 ST1100
            1999 ST1100
            North Georgia

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              #7
              You should be fine at 150. If you want to find out where you are leaking from do a leak down test. Fill the cylinder with air @ TDC, listen for where its coming out. That will let you know rings or valves.

              But unless its down on power or smoking, i'd keep riding it.
              Don't spend money and buy, spend time and learn.

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                #8
                It does feel a bit down on power. But I'm not sure if that's compression related. Or possibly carburetor related since it's sits a bit now cuz i got a 06 yzf-600r 6 months ago....which very well could be the only thing making feel slower lol idk

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                  #9
                  numbers seem good, especially for the piston rings. of course you held the throttle wide open ? engine hot or cold ?
                  squirrelman
                  Elite Hawker and Carburetor Master
                  Last edited by squirrelman; 10-09-2021, 08:08 PM.
                  "It's only getting worse."


                  MY rides: '97 VFR750, '90 Red Hawk, '88 Blue/Black Hawk, '86 RWB VFR700 (3), '86 Yamaha Radian, '90 VTR250, '89 VTR250 (2), '73 CB125, '66 Yamaha YL-1

                  Sold: '86 FJ1200, '92 ZX-7, '90 Radian, '73 CB750, '89 all-white Hawk, '88 blue Hawk, '86 FZ600, '86 Yam Fazer 700 , '89 VTR250, '87 VFR700F2, '86 VFR700F.

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                    #10
                    Engine hot i wanna say it was full throttle but 90% at least.

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                      #11
                      150 isn't terrible. Certainly not worth tearing the lump apart. Generally if you add a bit of oil into the cylinder and get a jump in compression that points to the rings, but again, I don't think you're at the new rings stage yet. I wouldn't worry until you see something like this:
                      Attached Files
                      ASMA #139

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                        #12
                        Right on I'll clean the carbs and see if that livens her back up. Hope the new bike didnt ruin the hawk for me lol

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                          #13
                          Okay now i take the uni pods off to see about cleaning them up and one slide is clean and the other is grimey as hell...any ideas why they are so different?

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