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    Lacking power please help!

    Hello, I am new here and to motorcycles and need some help. To start off my bike is a 1979 425 . The problem with the bike is it is lacking power. This has happened two other times before. while riding it will make this popping noise and the take off and regain power. hoping you guys can tell me what is causing this and how to fix it thank you in advanced.

    #2
    Sounds like one of the cylinders is dropping out.

    What maintenance have you performed?
    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

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      #3
      Bad plug wire connections, bad wire arching from time to time to the engine block, bad connections at the wiring harness for the coil leads, bad wiring harness grounding point, bad plug caps, plug itself going south, slight petcock blockage.... just for a few i can think of right now.
      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.

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        #4
        I have not done much i changed oil, spark plugs, new fuel.

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          #5
          Get 5 bottles of 90% rubbing alcohol..rinse the tank like mad with 3 of the bottles and then again with the other 2. It will cut any gelled slime off the walls of the tank. By like mad, I mean agitate it at all angles for at least 15 minutes with the "cutting" application and 5 for the "rinse".

          Next, if it has an inline fuel filter..look and see if its all brown and nasty looking..possibly clogged.

          Replace the fuel lines with new..yes rubber deteriorates and specks can get sucked into the jets.

          Set the valve adjustments per the manuals specs.
          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


            #6
            New air filter will let her breathe better too. Pull the petcock and check the screen there too.
            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


              #7
              Hi Greg and welcome!

              The other is to check the state of the spark plug caps. They can be dodgy and cause weak spark.

              Being a 425 means you have points as well, so check the state of the points, they made need adjusting, filing, or replacing.

              The other thing I have heard of is the condensors on the coils failing, so there's another possibility as well.
              1982 GS450E - The Wee Beastie
              1984 GSX750S Katana 7/11 - Kit Kat - BOTM May 2020

              sigpic

              450 Refresh thread: https://www.thegsresources.com/_foru...-GS450-Refresh

              Katana 7/11 thread: http://www.thegsresources.com/_forum...84-Katana-7-11

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