Bike not starting

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  • Mike

    #1

    Bike not starting

    Finally got my carbs put back together and tried to start it. Nothing. Just cranks and cranks. Every once in awhile, it'll fire for a split second when I let off the starter button, but other than that, it won't fire. I've got the battery hooked up to my car to make sure it's not low on juice (the car isn't running). I pulled the plugs and laid them on the head, and they're sparking. The bike ran before I pulled the carbs, so I can't imagine that the timing is off or anything too major.

    Thoughts?
  • Mike

    #2
    Also - I pulled the line from the tank and turned the petcock to prime and gas did come out.

    Comment

    • mike_of_bbg

      #3
      Did you "bench sync" the carbs before you put them back on? If one of the throttles is completely closed, it's unlikely a twin can start on just one. If one is too open it probably won't suck in enough fuel.

      Are you using choke or no?

      How many turns were the idle screws out before you disassembled the carbs? How many did you set them to putting them back on?

      Comment

      • tkent02
        Forum LongTimer
        Past Site Supporter
        • Jan 2006
        • 35571
        • Near South Park

        #4
        Originally posted by Mike
        Every once in awhile, it'll fire for a split second when I let off the starter button, but other than that, it won't fire.
        This is a clue, check the voltage to the ignition while the starter is turning. It sounds like the voltage is too low, so it's not sparking until you release the starter button.
        http://img.photobucket.com/albums/v5...tatesMap-1.jpg

        Life is too short to ride an L.

        Comment

        • Mike

          #5
          Originally posted by tkent02
          This is a clue, check the voltage to the ignition while the starter is turning. It sounds like the voltage is too low, so it's not sparking until you release the starter button.
          How would I do that? Like where exactly would I put the leads? I'll have to go pick up a volt meter tomorrow first

          Comment

          • tkent02
            Forum LongTimer
            Past Site Supporter
            • Jan 2006
            • 35571
            • Near South Park

            #6
            The orange and white wire going to the coils.
            http://img.photobucket.com/albums/v5...tatesMap-1.jpg

            Life is too short to ride an L.

            Comment

            • Mike

              #7
              This is the part of the thread where I am mocked mercilessly

              Took the carbs off and saw the problem immediately. I had the throttle cable horribly tight and the butterflies where about 30% open with the throttle off. Closed that up and it fired right up.

              NOW - it idles erratically and if I give it some gas, it dies. I'm assuming I just need to mess with the adjustment screws?

              Comment

              • Nessism
                Forum LongTimer
                GSResource Superstar
                Past Site Supporter
                Super Site Supporter
                • Mar 2006
                • 35790
                • Torrance, CA

                #8
                4) ?

                1A) (NEW) Trying to diagnose running problems on a bike with an unknown maintenance history. Common maintenance items like clean carbs, properly adjusted valves, no air leaks in the intake system (airbox, carb boots), a clean gas tank (no rust), and a properly functioning petcock are 100% mandatory for the bike to run properly.
                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

                • Mike

                  #9
                  Airbox is in place

                  Comment

                  • Mike

                    #10
                    One thing I will point out - I absolutely could NOT get those damn adjustment screws out when I was cleaning the carbs. They turn no problem, but getting them out of the body? Not happening. Other than that, I'm clueless.

                    Comment

                    • mike_of_bbg

                      #11
                      Did you dip the carbs? In what?

                      Yours is a twin so I'm not familiar with your carbs. The 4-cyl CV carbs have an o-ring under the idle screw, Berryman's or Gunk might well melt that.

                      Comment

                      • Nessism
                        Forum LongTimer
                        GSResource Superstar
                        Past Site Supporter
                        Super Site Supporter
                        • Mar 2006
                        • 35790
                        • Torrance, CA

                        #12
                        GS bikes are lean from the factory so they need to warm up before they will accept throttle. I assume the air filter is installed and the airbox lid is sealed up. You might want to set the pilot screws to 3 turns and see if that helps. Just so you know the bike won't run with plugged pilot jets and plugged choke tubes. Basically the carbs need to be spotless, you need fresh O-rings in the carbs, and you need fresh O-rings in the intake boots.

                        Good luck and hope this helps.
                        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

                        • Mike

                          #13
                          Pilot jets are brand new. All new rings in the carb (except for the adjustment screw).

                          Dipped both carbs in berryman's overnight.

                          Next step is to jb weld something to the screw to get it to come out (not permanently)

                          Comment

                          • Guest

                            #14
                            I used a tiny jewellers flat blade to get my mixture screws out.

                            Hard to describe, but I was able to slide it down under the lip of the head and "walk" it out. Tedious and painful, but being careful meant I didn't damage the new O rings either.

                            Comment

                            • Mike

                              #15
                              I'm wondering if I should replace the air filter as well. Maybe it got soaked and ruined when the airbox flooded with gas.

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