No compression after valve job still....

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  • hockey911
    • Feb 2026
    #1

    No compression after valve job still....

    I have 0 compression in either cylinder........

    what i did....

    Replaced 1 exhaust valve, lapped all 4 with grinding compound + suction cup... replaced stem seals... new head gasket...


    I dont know what is wrong, i timed the bike, rotated the engine a few times by hand verified no interference issues....

    Ran the starter with (old) sears compression tester (rubber type)

    not getting any compression in either cylinder....

    however when i place my hand over the intake boot i can feel a strong force pulling my hand in when the bike is cranking....

    also can feel air moving from exhaust........ any clues...

    i really dont want to pull the motor apart again..... :?
    Tags: None
    • Datsa Noydb
      Forum Mentor
      • Feb 2011
      • 200
      • State of Confusion
      #2
      If you can feel air moving at the intake and exhaust ports, I would seriously suspect your compression tester.

      Get one that threads in to the spark plug hole.
      I ride many bikes.
      Some are even Suzukis. :D

        Comment

        • BigD_83
          Forum Sage
          Past Site Supporter
          • May 2011
          • 4872
          • Vancouver
          #3
          Are you at wide open throttle when turning over? If so, I agree with Datsa Noyb
          '83 GS650G
          '83 GS550es (didn't like the colours in the 80's, but they've grown on me)

            Comment

            • Datsa Noydb
              Forum Mentor
              • Feb 2011
              • 200
              • State of Confusion
              #4
              He mentioned putting his hand over the "intake boot", rather than mentioning "carb intake", so I was guessing the carbs are not even installed.
              I ride many bikes.
              Some are even Suzukis. :D

                Comment

                • Guest
                  #5
                  Check your cam chain timing

                    Comment

                    • 8ball
                      Forum Mentor
                      • Nov 2012
                      • 230
                      #6
                      You shouldn't feel ANY force pushing out the intake boot!! Only suction. The intake valves should be closed every time the piston moves up
                      1979 GS550, 2003 R6, 1998 XR400 Dual Sport, 2004 V-Star.........

                      Decisions, decisions, what to ride, today.
                      sigpic
                      My GS550 Build

                        Comment

                        • Datsa Noydb
                          Forum Mentor
                          • Feb 2011
                          • 200
                          • State of Confusion
                          #7
                          Originally posted by 8ball
                          You shouldn't feel ANY force pushing out the intake boot!! Only suction.
                          Where did you get that idea?

                          Re-read his original statement:

                          Originally posted by hockey911
                          ... when i place my hand over the intake boot i can feel a strong force pulling my hand in when the bike is cranking....
                          I ride many bikes.
                          Some are even Suzukis. :D

                            Comment

                            • Guest
                              #8
                              Bad gauge...

                                Comment

                                • Nessism
                                  Forum LongTimer
                                  GSResource Superstar
                                  Past Site Supporter
                                  Super Site Supporter
                                  • Mar 2006
                                  • 35789
                                  • Torrance, CA
                                  #9
                                  Please tell us you performed a valve adjustment.

                                  Assuming yes, I'd double check the cam timing. It's sometimes difficult to see the marks on the advance unit.
                                  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

                                    • BigD_83
                                      Forum Sage
                                      Past Site Supporter
                                      • May 2011
                                      • 4872
                                      • Vancouver
                                      #10
                                      Originally posted by Datsa Noydb
                                      He mentioned putting his hand over the "intake boot", rather than mentioning "carb intake", so I was guessing the carbs are not even installed.
                                      Yes, point taken. I seem to be terminologically challenged over here in holiday land...
                                      '83 GS650G
                                      '83 GS550es (didn't like the colours in the 80's, but they've grown on me)

                                        Comment

                                        • hockey911
                                          #11
                                          Hi all happy holidays!


                                          Timing, i set the timing on the lower to T| (lined up the | with the | ), placed the exhaust cam pointing out, placed the intake cam in and made the two upper arrows 18 links apart from each other and put the tension on, i may still need shims... i just bought a feeler gauge and it appears that all of them are far out of spec..... well i cant get the smallest metric feeler under the cam and the bucket...


                                          maybe * this is causing my issue?


                                          this is how i set my timing... a picture is worth a thousand words lol
                                          http://ww2.justanswer.com/uploads/motoforge/2010-09-04_002115_GS450camtiming.jpg

                                            Comment

                                            • Nessism
                                              Forum LongTimer
                                              GSResource Superstar
                                              Past Site Supporter
                                              Super Site Supporter
                                              • Mar 2006
                                              • 35789
                                              • Torrance, CA
                                              #12
                                              Originally posted by hockey911
                                              Hi all happy holidays!


                                              Timing, i set the timing on the lower to T| (lined up the | with the | ), placed the exhaust cam pointing out, placed the intake cam in and made the two upper arrows 18 links apart from each other and put the tension on, i may still need shims... i just bought a feeler gauge and it appears that all of them are far out of spec..... well i cant get the smallest metric feeler under the cam and the bucket...


                                              maybe * this is causing my issue?


                                              this is how i set my timing... a picture is worth a thousand words lol
                                              http://ww2.justanswer.com/uploads/mo...0camtiming.jpg
                                              There are two T marks. One for the right cylinder and one for the left. You need to put the crank at T for the Right cylinder. Pull the spark plugs and make sure you can see the piston at the top through the spark plug hole.

                                              Regarding the valves, wish I was surprised. You should be ashamed.
                                              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

                                                • hockey911
                                                  #13
                                                  Originally posted by Nessism
                                                  There are two T marks. One for the right cylinder and one for the left. You need to put the crank at T for the Right cylinder. Pull the spark plugs and make sure you can see the piston at the top through the spark plug hole.

                                                  Regarding the valves, wish I was surprised. You should be ashamed.



                                                  Do you know what diameter shims i need for a 1982 gs450tx?

                                                    Comment

                                                    • Who Dat?
                                                      Forum Mentor
                                                      • Jun 2012
                                                      • 461
                                                      • On the edge.
                                                      #14
                                                      The diameter will be 29.5mm. The thickness will depend on what you have in there now. You said you can't get your thinnest feeler in, but did not mention the thickness of the feeler. The clearance on these valves is VERY thin, 0.03-0.08mm, which is close to 0.0015"-0.003". Those are usually the thinnest feelers in a set.

                                                      Be careful if you get your shims at a multi-brand dealer. Kawasaki and Yamaha have shims that are 29,0mm in diameter and look very close, you have to measure them. Shims are available on eBay. You can also order them from Z1 Enterprises for about the best price going. Many have also joined the GSR "Shim Club" and reported success and happiness, so look that one up, too.

                                                      While you are in this process, look up member "Steve", he has a spreadsheet that helps you figure out what shim you need and helps you keep track of what is in your bike and what it will need next.
                                                      If you're not living on the edge, you're taking up too much space.

                                                        Comment

                                                        • hockey911
                                                          #15
                                                          Figured it out.... it was the shims.....

                                                          K&L shim starter kit ordered!

                                                          She holds compressed air when the shims are out (not cranking the motor)... and leaks like a son of a gun when the shims are in.... thanks!!

                                                            Comment

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