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    #1

    spark timing

    Hi all. im new here, i hope you can help me. i have a 1981 gs450l. it runs on one cylinder, it has spark to both and fuel to both. Good compression on both. so in theory, it has everything to fire on both cylinders but it will only fire on the right cyl. im presuming that it is a problem with spark timing, what is the cause, cdi or pickup? or something else. if it is either of those, where can i get a replacement unit, everything online is used, anything new seems to be a crazy price. with carbs off, spraying easy start into each cylinder, it fires on the right, nothing on the left despite having a strong spark and good compression, so that eliminates a fuel problem.
    thanks in advance.
    Last edited by mikefitz1000; 11-01-2022, 08:30 AM.
    Tags: None
    #2
    How are you sure you have spark to both?
    Have you swapped plugs and HT lead end caps and checked the core of the HT lead at the end for corrosion?
    97 R1100R
    Previous
    80 GS850G, 79 Z400B, 85 R100RT, 80 Z650D, 76 CB200

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      #3
      Yeah thats all done. strong blue spark to both plugs. it looks like the left one must not be timed right. so thats the answer im looking for.

      Comment

        #4
        Have a look at this thread.

        gs450 timing issue? - The GSResources Forums
        https://www.thegsresources.com/_forum/forum/technical-forums/electrical-ignition/73547-gs450-timing-issue
        Place your GS electrical or ignition related questions in this forum.
        97 R1100R
        Previous
        80 GS850G, 79 Z400B, 85 R100RT, 80 Z650D, 76 CB200

        Comment

          #5
          yeah that goes on about valves and carbs. all that is done valves reseated, clearance perfect, perfect compression, valve timing perfect, definitely not a fuel issue as i said, carbs off squirt easy start in to right, it fires, into left, nothing. spark on both is perfect, it must be spark timing, but i dont know anything about how to fix that

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            #6
            im thinking cdi unit or pickup or both. Does anyone know where i can get them?

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              #7
              Your bike doesn't have a CDI.

              You might want to try a shot of starting fluid in the airbox to see if the 2nd cylinder fires. If it does, you have carb problems.
              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

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                #8
                You'll find more help in the https://www.thegsresources.com/_foru...rical-ignition section. THIS section is for 'General Information about the forum, not motorcycles.

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                  #9
                  Hi folks. update on the problem. as I thought it was the cdi unit. a new bespoke unit from ignitech.cz solved the problem. well done to them, they are professional and helpful. they can be contacted at
                  ignitech@ignitech.cz
                  • Likes 2

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