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'77 GS750. Spark, no spark.

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    '77 GS750. Spark, no spark.

    My poor bike. I didn't ride it once this summer. I did add fuel stabilizer and octane boost last fall. I did start it once or twice this summer and it fired up. Now that I actually hauled it out of the shed, it fired up for 10 seconds. Now, zero spark. Can a bad voltage regulator cause this intermittent problem? Last year, even when the bike was running I never got more than 12V at the battery. The bike ran fine 0-5k RPM but very rough after 5k. Could this be a symptom of a bad regulator?
    Any quick things to look at?
    Thanks

    #2
    Is the shed cold and damp?

    Comment


      #3
      Charge battery and check points. In other words, basic maintenance.
      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


        #4
        I know...basic stuff. But I did a ton of stuff last summer. I bascially read and followed Cliff's site to the T. Carbs dipped, sealed, new O-rings all new intake rubber. New coils, wires plugs. I suppose I should start with a regulator change. I was just hoping someone else might have had a similar intermittent problem. Points are clean and gapped. I never set the timing, but, if it was bad it wouldn't be intermittent. Can a bad regulator cause this??

        Comment


          #5
          We found on my buddies 850 that there was corrosion on in the kill switch on the handle bar.

          Comment


            #6
            A bad regulator will cause the battery to run down. Typically though if there is enough juice to spin the engine via the starter, there should be plenty to throw spark.
            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
              I vote for clean the connections first. I had an 80 750T that had no charging voltage at all and the stator was throwing 70 at all 3 legs. Ceaned the regulator connections and had 13.9 at the battery instantly.

              So a cold damp storage environment could have corroded some things and they need some cleaning and dielectric grease applied.
              MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
              1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

              NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


              I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

              Comment


                #8
                Thanks..I guess thats my next step. I will clean all the connections.
                The bike is super clean, 40,000km (25k miles) and I have yet to have it running properly.
                It was stored in a cold damp shed. Just kind of strange that it started several times in the last few weeks, then as soon as I haul it out of the shed, it starts instantly, idles at 3k for 5 seconds....then dies. No spark.

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