79 gs550 only running on spray

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • TwoWheelKid
    • Jan 2026

    #1

    79 gs550 only running on spray

    Hey guys, be easy on me I'm new here and this is my first motorcycle. I'm mechanically inclined but this one has got me stumped.. Its a 1979 GS550 with VM carbs that I've taken apart and soaked for a day. Put them back together and the bike still won't run unless I spray gas in the intake side of the carbs. I set the bottom air/fuel screws at 3/4 of a turn and the side ones at 1 1/2 turns. Jets are 80 main and 50 idle. Fuel in all four carbs when I open the drain. Also when I was cranking on it a ground wire melted under the seat and I no longer have electric start!!
  • tom203
    Forum Guru
    Past Site Supporter
    • Aug 2010
    • 8925
    • Norway,Maine

    #2
    Do you understand use of "choke" system? Does it appear that you have healthy spark at plugs?
    1981 gs650L

    "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

    Comment

    • TwoWheelKid

      #3
      Still won't fire with the choke on, and yes, lots of spark at the plugs.


      Originally posted by tom203
      Do you understand use of "choke" system? Does it appear that you have healthy spark at plugs?

      Comment

      • cornishgs
        Forum Apprentice
        • Sep 2014
        • 76
        • Redruth,Cornwall, United Kingdom

        #4
        Did you bench sync them? also is it fresh gas(petrol, stale wont fire up so well.
        Originally posted by TwoWheelKid
        Hey guys, be easy on me I'm new here and this is my first motorcycle. I'm mechanically inclined but this one has got me stumped.. Its a 1979 GS550 with VM carbs that I've taken apart and soaked for a day. Put them back together and the bike still won't run unless I spray gas in the intake side of the carbs. I set the bottom air/fuel screws at 3/4 of a turn and the side ones at 1 1/2 turns. Jets are 80 main and 50 idle. Fuel in all four carbs when I open the drain. Also when I was cranking on it a ground wire melted under the seat and I no longer have electric start!!
        Last edited by cornishgs; 05-03-2015, 04:01 PM.

        Comment

        • TwoWheelKid

          #5
          Yep bench synched and fuel is fresh

          Originally posted by cornishgs
          Did you bench sync them? also is it fresh gas(petrol, stale wont fire up so well.

          Comment

          • cornishgs
            Forum Apprentice
            • Sep 2014
            • 76
            • Redruth,Cornwall, United Kingdom

            #6
            If plugs are all dry and it wont fire carbs need checking again- float heights,internal passageways,choke plungers operating fully ,try opening fuel screws more,blocked idle circuit.

            best double check stuff already done its the only way. pain in the ass but all jets need poking through with fine wire to really check .

            Comment

            • gustovh
              Forum Sage
              Past Site Supporter
              • Oct 2006
              • 4979
              • Vernonia

              #7
              Is the fuel line attached correctly, the T between #2/3 carbs? Low compression will cause a no start issue as well.

              V
              Gustov
              80 GS 1100 LT, 83 1100 G "Scruffy"
              81 GS 1000 G
              79 GS 850 G
              81 GS 850 L
              83 GS 550 ES, 85 GS 550 ES
              80 GS 550 L
              86 450 Rebel, 70CL 70, Yamaha TTR125
              2002 Honda 919
              2004 Ural Gear up

              Comment

              • Big T
                Forum LongTimer
                Past Site Supporter
                Super Site Supporter
                • Mar 2005
                • 12365
                • West Slope, OR

                #8
                TWK,

                Check the holes that the fuel needles (underneath) go into.

                Someone may have tightened the needles too much and snapped off the tips, clogging the pilot circuit
                1978 GS 1000 (since new)
                1979 GS 1000 (The Fridge, superbike replica project)
                1978 GS 1000 (parts)
                1981 GS 850 (anyone want a project?)
                1981 GPZ 550 (backroad screamer)
                1970 450 Mk IIID (THUMP!)
                2007 DRz 400S
                1999 ATK 490ES
                1994 DR 350SES

                Comment

                • cornishgs
                  Forum Apprentice
                  • Sep 2014
                  • 76
                  • Redruth,Cornwall, United Kingdom

                  #9
                  did you fix it?

                  Comment

                  • TwoWheelKid

                    #10
                    Yes, ended up being incorrectly set floats, was only running on cylinder #1 & #3. Set the floats to 22.4MM and all good now.
                    Originally posted by cornishgs
                    did you fix it?

                    Comment

                    Working...