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    Are my intake valves bent?

    Hi all,

    Well this all started as simple base gasket replacement.
    In the process of re-installing the cams, I forgot to time the crankshaft before I timed the cams. So long story short, I had complete valve to piston contact. I was using a wrench on the crankshaft bolt to turn it. It turned with slight contact. I then realized my error.What are the chances the valves are bent? I put about 100 psi of compressed air to each cylinder and they all blew air back out the intakes. I then removed the head to view the damage. They don't look bent or scarred but I do see where the made contact on the piston. Can excess carbon cause the compressed air to escape? I then sprayed in some carb cleaner and #1 cyl seeped just a little. What should I be looking for and or doing? If the valves are bent, what is involved in replacing them?

    thanks

    Scott

    #2
    I doubt the valves are bent unless you used a lot of force on the wrench turning over the engine, or if you hit the starter button.

    While the head is back off you should remove the valves, clean them up, lap them into their seats, and install fresh valve stem seals. Check Basscliff's site for Steve's video on this matter. It's pretty easy to do and well worth the time.
    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


      #3
      just installing and tightening the cams down in the wrong position can bend(tip) the valve(s) that make contact with the piston(s).

      Comment


        #4
        i'd like to add this sense you do not mention what model of GS you have.
        a 16 valve model is more likely to "tip" a valve rather than an 8 valve model.
        the 8 valvers are much larger and more resistant to damage because of the size difference.
        if you have a "twin" then chances are that your ok unless you felt a lot of pressure while you was tightening the cam caps.

        Comment


          #5
          yes i was stupid and hit the starter button thinking all was well.

          Comment


            #6
            Originally posted by scottsgs View Post
            yes i was stupid and hit the starter button thinking all was well.
            Not good.

            I'd pull out the valves and have a look see. It shouldn't be too hard to find some new/used valves - post an ad in the Parts Wanted forum once you confirm what you need.

            A trick to help you remove the valves quickly...

            Remove the valve buckets over the valves, stuff a rag in the combustion chamber (enough to fill it up), flip over the head capturing the rag in place, then take a good sized deep socket, position it over the top of the valve spring and give it a good whack with a hammer. The valve spring will compress just enough for the keepers to jump out of place so you can remove the spring. Squaredance Lynn told me about this trick years ago and it works a treat.
            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


              #7
              Originally posted by Nessism View Post
              Not good.

              I'd pull out the valves and have a look see. It shouldn't be too hard to find some new/used valves - post an ad in the Parts Wanted forum once you confirm what you need.

              A trick to help you remove the valves quickly...

              Remove the valve buckets over the valves, stuff a rag in the combustion chamber (enough to fill it up), flip over the head capturing the rag in place, then take a good sized deep socket, position it over the top of the valve spring and give it a good whack with a hammer. The valve spring will compress just enough for the keepers to jump out of place so you can remove the spring. Squaredance Lynn told me about this trick years ago and it works a treat.
              I used the same trick for rebuilding small block Chevy heads.

              Comment


                #8
                i guess my visions going bad...
                so he posted he has an 8 valve shim bucket model GS
                i never seen a make or model posted
                i'm headed to lens crafters

                Comment


                  #9
                  Originally posted by blowerbike View Post
                  i guess my visions going bad...
                  so he posted he has an 8 valve shim bucket model GS
                  i never seen a make or model posted
                  i'm headed to lens crafters

                  one of his first posts (not in this thread) says

                  .....81 GS850G

                  Comment


                    #10
                    ok multiply threads.....
                    kreskin i am not

                    Comment


                      #11
                      Originally posted by blowerbike View Post
                      ok multiply threads.....
                      kreskin i am not
                      I just did a quick scan of "find all posts by"

                      Comment


                        #12
                        Originally posted by Nessism View Post
                        Not good.

                        I'd pull out the valves and have a look see. It shouldn't be too hard to find some new/used valves - post an ad in the Parts Wanted forum once you confirm what you need.

                        A trick to help you remove the valves quickly...

                        Remove the valve buckets over the valves, stuff a rag in the combustion chamber (enough to fill it up), flip over the head capturing the rag in place, then take a good sized deep socket, position it over the top of the valve spring and give it a good whack with a hammer. The valve spring will compress just enough for the keepers to jump out of place so you can remove the spring. Squaredance Lynn told me about this trick years ago and it works a treat.
                        If using a spark plug socket, just wrap a single wrap of black electrical around the socket so as not to score the shim bucket bore.

                        Comment


                          #13
                          I have looked at the valves and pistons up close. There appears to be no damage. It was only light contact, similar to having 1 spark plug in a hole as you turn the crank by hand, again very light resistance. This when I hit the starter thinking I was feeling the stator magnets. My bad. I will be taking the head to a buddies shop on Wed. to pull the valves and if all is well, I plan on lapping them.

                          I believe what may be my saving grace was the carbon on top of the pistons. I will be installing new valve guide seals because I see some oil leakage as well.

                          I will post my findings ASAP.

                          Scott

                          Comment


                            #14
                            hi all,

                            Okay, so here's an update on my valve situation. It's good news. None of the valves bent. I lapped them all and installed new oil seals. Lesson learned!

                            Thanks for all the help.

                            Scott

                            Comment


                              #15
                              Few!!!!! that's good..having a bent valve is no way to go through life...
                              Last edited by Guest; 08-11-2010, 09:56 PM.

                              Comment

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