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rings and valve lapping, still low compression???

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    rings and valve lapping, still low compression???

    HI AGAIN,
    I have an 82 GS850G. I had low compression in #3, 90 PSI, so I took cylinder head off and while I was at it I might as well do the rings. I bought Genuine Suzuki Parts standard rings. The cylinders were all within specs, maybe a thousands off. Rings measured inside cylinder and had at least a .004 thousandths gap. Ring slots placed properly. I put on all new Vesrah gaskets. Lapped in the valve and after a gasoline test, no leaks. Now I never had great compression, never over 140 PSI and I have owned this bike for almost 8 years. My compression, hot, was 132. 132.128.139 respectively. Any suggestions why my compression is so low or did I leave any steps out? Book says 129-171 PSI is compression range.

    #2
    Valves adjusted properly? Valve timing off?
    1984 GS1100GK newest addition to the heard
    80 GS 1000gt- most favorite ride love this bike
    1978 GS1000E- Known as "RoadKill" , Finished :D
    83 gs750ed- first new purchase
    85 EX500- vintage track weapon
    1958Ducati 98 Tourismo
    “Remember When in doubt use full throttle, It may not improve the situation ,but it will end the suspense ,
    If it isn't going to make it faster or safer it isn't worth doing

    Comment


      #3
      What type of hone and what grit was used to deglaze the cylinders? What processes did you use to break in the rings? Baby the engine or run it hard, or medium?
      Ed

      To measure is to know.

      Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

      Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

      Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

      KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

      Comment


        #4
        I used a friends honing triple stone , I don't know the grit. I'll check with I'm. As far as valve adjustment I have adjusted the valves three different times. I have them opened to .004 on the intake and about .003 on the exhaust to let more air in and that is the present reading. Timing is right on. The bike runs really good, I was just concerned about the low compression. I haven't broken in the rings or valves, all I have done is ride the bike around the neighborhood a couple of times. Should I give it a couple hundred miles and do a compression check then?
        Last edited by Bob Shaw; 02-12-2017, 11:30 AM. Reason: just a correction.

        Comment


          #5
          Sounds like you're still running in. Those numbers are ok - and they're pretty even.

          Plus are you sure your compression tester reads accurately. Mine reads low consistently.
          79 GS1000S
          79 GS1000S (another one)
          80 GSX750
          80 GS550
          80 CB650 cafe racer
          75 PC50 - the one with OHV and pedals...
          75 TS100 - being ridden (suicidally) by my father

          Comment


            #6
            Originally posted by hampshirehog View Post
            Plus are you sure your compression tester reads accurately. Mine reads low consistently.
            Good thing to check. Mine always reads exactly 90 psi on all four cylinders of a perfectly good running bike.
            https://drive.google.com/open?id=0B9zH8w8Civs8ejBJWjdvYi1LNTg&resourcekey=0-hlJp0Yc4K_VN9g7Jyy4KQg&authuser=fussbucket_1%40msn.com&usp=drive_fs
            1983 GS750ED-Horsetraded for the Ironhead
            1981 HD XLH

            Drew's 850 L Restoration

            Drew's 83 750E Project

            Comment


              #7
              Originally posted by hampshirehog View Post
              Sounds like you're still running in. Those numbers are ok - and they're pretty even.

              Plus are you sure your compression tester reads accurately. Mine reads low consistently.
              Agreed with the numbers being OK. Takes a while for the compression to come up after a re-hone and those look in decent condition. Ride the hell out of it and do a good amount of open throttle runs through the gears. Don't cruise at constant speeds.
              http://img633.imageshack.us/img633/811/douMvs.jpg
              1980 GS1000GT (Daily rider with a 1983 1100G engine)
              1998 Honda ST1100 (Daily long distance rider)
              1982 GS850GLZ (Daily rider when the weather is crap)

              Darn, with so many daily riders it's hard to decide which one to jump on next.;)

              JTGS850GL aka Julius

              GS Resource Greetings

              Comment


                #8
                Those three blade hones aren't the best for deglazing. The dingo ball type is better, in 240 grit.

                I'd give that bike of yours the ol Italian tune up (ride the crap out of it). Last thing you want to do is baby it.
                Ed

                To measure is to know.

                Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

                Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

                Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

                KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

                Comment


                  #9
                  Thanks to all of you. I'll ride it and test it again after everything gets seated in. Thanks again....

                  Comment


                    #10
                    Originally posted by Nessism View Post

                    I'd give that bike of yours the ol Italian tune up (ride the crap out of it). Last thing you want to do is baby it.
                    Never heard of an Italian tune up before but he is right. Ride the crap out of it for break in. Usually they say about 300 miles before everything is seated. The extra hard acceleration actually forces the rings up against the cylinder walls causing them to "seat" more quickly and more uniformly.

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