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Compression reading's.what do these figures mean?

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    Compression reading's.what do these figures mean?

    I am starting on my 3rd gsx1100 in as many months.This bike is very rough condition and has donated all it's good bit's to the other 2 but the engine has been unmolested and it runs great,so I was thinking of using it as a rat run around.The motor blows a bit of blue smoke when hot,so I did a compression test,expecting rings and valves to be pretty worn.This is the reading's DRY/WET that I got and I have come to the conclusion that,it must be Keep in mind I have limited experience and only know the basics.
    Engine full operating temp.
    160/200
    130/173
    130/172
    150/210

    Manual says 128psi to 174psi with a service limit of 100psi.
    To my logic this motor has no sealing issues either rings of valves.
    Any input appreciated.

    #2
    [qThis is the reading's DRY/WET that I got and I have come to the conclusion that,it must be worn valve stem seals Keep in mind I have limited experience and only know the basics.
    Engine full operating temp.
    160/200
    130/173
    130/172
    150/210

    Manual says 128psi to 174psi with a service limit of 100psi.
    To my logic this motor has no sealing issues either rings of valves.
    Any input appreciated.I have checked that breather is not blocked.

    Comment


      #3
      What sort of milage on the engine?

      I would not be too keen to rip it apart with those figures. Could be the valves not seating or tight.

      Suzuki mad.

      Comment


        #4
        Originally posted by Suzuki mad View Post
        What sort of milage on the engine?

        I would not be too keen to rip it apart with those figures. Could be the valves not seating or tight.

        Suzuki mad.
        unknown mileage but it is goes harder than my restored bike which stock exhaust and jets .
        valve clearances are perfect.even worn valve guides would leak compression to some degree.
        That only leaves valve seals to account for the blue engine smoke as oil is getting into the cylinders somehow.I have very limited hands on experience with these engines
        and I am just reading the manual.I was hopeing someone who knows these engines well could head me in the right direction.the plugs are reading perfect with no sign of oil and yet when it's hot a steady trail of blue smoke comes out the exhaust?.It is very hard to figure out why this bike is smoking. It only does it when its fully hot.one of my other bikes was also blowing blue smoke but it had a broken ring and scored bore on number 3.

        Comment


          #5
          highspeed: if you have the means a leakdown test would certainly be useful in determining exactly what the weak link is in your cylinders,,,,good luck to you

          Comment


            #6
            I'd suggest a plug chop when the engine is fully warmed up and under load. There is a chance that you are running slightly rich on #'s 2 and 3. Are you sure that the smoke you are seeing, is oil?

            Comment


              #7
              Not sure about a 1100 but the factory Suzuki manual for my 550 states the max acceptable difference in compression between cylinders is 28psi.

              If the engine is burning oil like you state there is a problem. Rings are the obvious answer since valve stem seal leaks usually show up as blue smoke on start up and deceleration. Plus, the wet test shows significant increases in compression. The readings themselves seem high, particularly the wet numbers. How confident are you in that gauge? Could be it's reading high and those 130's are really 110's?
              Last edited by Nessism; 08-21-2007, 10:08 AM.
              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

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

              Comment


                #8
                Originally posted by Dave8338 View Post
                I'd suggest a plug chop when the engine is fully warmed up and under load. There is a chance that you are running slightly rich on #'s 2 and 3. Are you sure that the smoke you are seeing, is oil?
                No not 100% sure but I thought if it was running rich the smoke was always going to be black not white/blue.I just held a clean white rag over the exhaust outlet for a couple of minutes and it does no show or smell of any oil deposits but the smoke is there and I noticed the bike did not start smoking for sometime after I got back and it had been idling.

                The figures for compression are correct and gauges SAE and good quality.

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