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    No start issue fuel related

    I have an '83 GS550L. I bought it non running. Replaced the coils. Had the carbs rebuilt. Replaced the stator that was fried. It will not start. It will fire up if I apply positive air pressure(blow into) the float bowl breather.

    my theory is vacuum leak. I don't know a lot about bikes. This is my first. I'm good with cars. I don't even know where to begin. Any help would be greatly appreciated.

    also of note. I don't have the air box. The mufflers are gone from previous owner.

    #2
    When I get it to fire up by blowing into the tube the engine races and throttle or choke has no effect.

    Comment


      #3
      Check the Newbie Mistakes thread linked in my signature to see if anything applies.
      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
        After checking the Newbie Mistakes thread, check your valve clearances and possibly your starting technique.

        If the valves are too tight (especially the intakes), you will have a hard time starting the bike, because some of the mixture gets blown back through the carbs, instead of staying in the cylinder to get burned. Tight valves also lead to BURNT valves, which gets expensive, so spend a little bit of time to check the clearances.

        The starting technique for these bikes is a bit different than the cars to which you are accustomed. The "choke" does NOT choke the intake of the carb, it is actually a separate circuit in the carb that provides a richer mixture for starting the bike. It relies on the high vacuum of a CLOSED throttle, so if you "pump" the throttle to aid starting, you are actually hurting the process, not helping it. There is no accelerator pump, so "pumping" the throttle is a useless effort. Just turn the petcock to PRIme to allow the bowls to fill, set the "choke" lever to about FULL, turn the key ON, pull the clutch lever, push the starter button. Do NOT touch the throttle. If the engine starts and runs too fast, move the "choke" lever to adjust speed.

        You have any idea what was done to the carbs when they were "rebuilt"? Blowing into the vent lines will pressurize the bowls, putting some fuel into the carb throats, but not necessarily through the proper ports. If the carbs were not CLEANED properly and just had some new parts thrown in, they were not properly rebuilt.

        Having no airbox is not a good thing, but should not prevent the bike from starting. However, having no mufflers is worse, but probably needs clarification. Were the mufflers cut off the header pipes? (You still have header pipes but no mufflers?) Or do you have NO exhaust system on the bike and can see the exhaust valves operating through the ports? That is even worse, the bike should not be run like that. If you plan on running the bike with no mufflers, the help stops now, but if you plan on adding mufflers, we can continue.

        .
        sigpic
        mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
        hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
        #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
        #2 son: 1980 GS1000G
        Family Portrait
        Siblings and Spouses
        Mom's first ride
        Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
        (Click on my username in the upper-left corner for e-mail info.)

        Comment


          #5
          I'm going to add mufflers I simply want to make sure it's running before I get too carried away. The mufflers were cut off of the header pipes which are installed on the bike. In this picture the choke cables are hanging down but have since been installed. I will check the news thread.
          IMG_6403.jpg

          Comment


            #6
            Thank you for planning to add mufflers, the help session can continue.

            Check the local Harley shop to see if they have any Sportster take-offs.
            Nice, slim look, a bit throatier than stock and probably stupid cheap.

            .
            sigpic
            mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
            hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
            #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
            #2 son: 1980 GS1000G
            Family Portrait
            Siblings and Spouses
            Mom's first ride
            Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
            (Click on my username in the upper-left corner for e-mail info.)

            Comment


              #7
              I'm also generically wondering if they did a rebuild and didn't do any kind of adjustment. I'm assuming that the butterflies should close all the way and that idle air comes in from elsewhere yes?

              Comment


                #8
                "I'm assuming that the butterflies should close all the way and that idle air comes in from elsewhere yes?"

                Yes, the throttle plates will appear just about fully closed sitting on idle stop screw . A little extra mixture is sucked up thru some holes machined in carb throat. These criitters are hard to start cold unless the enrichment system (the "choke") is functioning. There are lots of little passages that get plugged up and resist quickee cleaning techniques.
                Read the newbie mistakes link to learn what needs to be done.
                1981 gs650L

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

                Comment


                  #9
                  No airbox & mufflers = FAIL
                  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


                    #10
                    Could these things really be that finnickey?

                    Comment


                      #11
                      hahahahahh yes
                      no start without airbox is likely
                      I once got mine to start without exhaust and it made sad sickly noises like suction cups being removed

                      and the airbox is a pita to install U lever mine with a 2x4 ever so gently
                      8 foot long or better
                      1983 GS 550 LD
                      2009 BMW K1300s

                      Comment


                        #12
                        I've ordered an air box and some mufflers. I'm not even going to bother trying until they get here. I'll keep you posted.

                        Comment


                          #13
                          So I got the air box. It's from an 83 gs550e according to the writing on it. Is this the same as the 550l? It has to be different or then lots have to be different because the bolt holes don't line up.

                          i'm also trying to remember tearing it down...the valve cover vent goes to the air box...does also the carb vent that I've been blowing into? There are two possible locations for it to receive tubes.

                          Comment

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