degreed cams now exhaust valve hits

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  • stain
    • Jan 2026

    #1

    degreed cams now exhaust valve hits

    Bike was running, degreed cams, now exhaust valve hits piston? Do these valves run that close to the piston that a few degrees can make them tag the pistons? The head has been cut but it ran 1500miles before I degreed the cams.
  • Guest

    #2
    Are the cam notches pointing at each other at TDC?

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    • posplayr
      Forum LongTimer
      GSResource Superstar
      Past Site Supporter
      • Dec 2007
      • 23673
      • Tucson Az

      #3
      cams are now un-degreed

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      • sharpy

        #4
        I disagree in how you degreed your cams and agree you have to degree your cams again. All agree?

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        • GregT
          Forum Sage
          • Jul 2009
          • 3541
          • New Zealand

          #5
          Concur....

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          • hampshirehog
            Forum LongTimer
            Past Site Supporter
            • Oct 2007
            • 12675
            • Hampshire. UK

            #6
            To a high degree there appears to be a degree of agreement in this thread......

            Sorry - you asked a sensible question and some of us couldn't refrain . The valves do run close to the pistons but my guess is that you haven't set something up right. Check and double check your starting point - dead easy to mess it so I always double check my double checking.
            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

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            • stain

              #7
              Installed ajustable gears dead center of slots. Set timing marks as--#1 on exhaust gear flush with head at timing mark T1-4. Slots on cams facing each other at TDC. Ran bike. Found true TDC. Remove all valve lash on #1 intake and exhaust valve. Proceeded to measure and adjust cams. Remeasured 8-10 times each side.
              What I can't understand is that if I set the gears off a tooth wouldn't my measurements be way off? If the gears were off would there even be enough adjustment in the slots to get correct numbers? It seems that exhust valve is the one touching the piston.
              The head is cut 40 thou

              Comment

              • sharpy

                #8
                Skimming the head will alter cam timing and make the cam chain "too long" But doing what you do should fix that. (i presume) Have a look down the LHS for cam timing instructions...



                The simply things that you miss are the ones that make your brain hurt. Could be worse, you could have just used the starter button to wind it over instead of by hand. Must be something you missed, sorry

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                • GregT
                  Forum Sage
                  • Jul 2009
                  • 3541
                  • New Zealand

                  #9
                  What lobe centers did you time it to ?

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                  • Guest

                    #10
                    With the TDC1&4 and the notches facing each other are the valves on #1 all closed?
                    How many chain links are between #2 and #3 sprocket arrow? Did you count the links above the arrows?
                    You can install the cam sprockets 180 off. Ask me how I know
                    How did you find TDC? Was it close to the stock marks?
                    Last edited by Guest; 06-05-2011, 02:21 PM.

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                    • stain

                      #11
                      I just checked true TDC again. True TDC was different than the factory marks by about the width of the mark.
                      Slots in cams facing inwards, All marks on gears as they should be.
                      The valves at #1 cylinder (left) are NOT fully closed, the cam is just starting to come on to the shims. They ARE closed on #4 (right)
                      I degreed the cams from #1 (left) cylinder.
                      20 pins between marks 2 on the exhaust gear and #3 on intake gear
                      I see how it can be easy to put the gears on 180 off

                      Comment

                      • stain

                        #12
                        Got it figured out. Thanks to the few that REALLY tried to help.
                        The cams WERE degreed correctly and the tool was set correctly.
                        Thanks Ray

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                        • posplayr
                          Forum LongTimer
                          GSResource Superstar
                          Past Site Supporter
                          • Dec 2007
                          • 23673
                          • Tucson Az

                          #13
                          Originally posted by stain
                          Got it figured out. Thanks to the few that REALLY tried to help.
                          The cams WERE degreed correctly and the tool was set correctly.
                          Thanks Ray

                          So you are not going to share what was wrong?

                          Comment

                          • sharpy

                            #14
                            Originally posted by posplayr
                            So you are not going to share what was wrong?
                            That what i was thinking. Didnt say what lobe centres it was timed at either

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                            • rapidray
                              Forum Guru
                              GSResource Superstar
                              • Oct 2006
                              • 8195
                              • So Cal

                              #15
                              Glad to help man! How's it pull from 6000-9500? Ray.

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