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81 GS750 STARTING PROBLEMS!!!!!!!

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    #1

    81 GS750 STARTING PROBLEMS!!!!!!!

    OK, I am restoring a 1981 GS750. I have trouble shot the electrical system and all works good there now. The bike sat for 3 years and needed some TLC. I took off the carbs and cleaned them. They were bad. filled with varnish. The main jets were completely plugged. I cleaned them and used a metal probe to loosen up the grime in the main jets, while they were off the carbs. I used carb cleaner and compressed air to blow through everything. When I blow air through each jet, or hole, it is not restricted and comes out the proper place. I reinstalled the carbs and hooked up the tank. I turned the petcock to prime and the carbs are getting gas. I have confirmed this y loosening the drain bolts on the float bowls and gas runs out. I tried starting the engine without the air box installed, just to see if everything was working. The engine cranks, but will not start. It appearred that the main jets are pointing towards the air box, is this correct. If so, I put my hand over them and while cranking it I felt pressure coming from them, however I did not get any gasoline on my hand. Do I need to prime something in the carbs??? I thought that maybee the air box had to be installed to work. I put the air box and air filter on, and still does not stary. I have tried the choke in all different positions and it doesn't seem to help. I am trying to start in the prime position, does it have to be in run, I have tried a couple of times without any positive results. When it has sat a little while I can push the start button and just for a split second I acts like it wants to start, then just cranking after that. It is acting like it isn'y getting any gas. I can spray starting fluid in the air box and it will start, then die. I know everything else is working, because of the starting fluid. I have replaced the spark plugs, and they all have good spark. everything else works. I would guess it is somewhere in the carbs, but am stuck on where to look. The carbs were dry as a bone when reinstalled, like I said I used carb cleaner and compressed air.

    Thanks for any help, this is driving me crazy
    Tags: None
    #2
    Yo bro I am in the EXACT same boat as you execpt mine was perfectly running 3 or 4 months ago and didnt have varnish for gas in the carbs.

    Keep an eye on my post here "GS650 will NOT start" I'll tell you what I have learned so far with regards to some of your questions.

    I have read a few times on the internet that the airbox and even air filter need to be installed for the bike to run or run well sometimes, and sometimes its fine without it on. But everyone seemed to agree that it atleast ran better with the airbox and cleaner on, I think it would just get too much air mixture without the box.

    Do your floats float? remove them and stick em in gas and hold them under for a sec to see if you get any air bubbles coming out of them, if you do you will need to replace the float. Are your floats set to the right depth? I assume you know how to adjust your floats if not just reply and I'll help you out.

    I dont believe your pecock needs to be on run for it to run, back when my bike ran.. It started in every position, I guess it might be possible to flood the carbs though if you leave it on prime.

    You said it will kind of start when you allow it to sit a while, that sounds like it could be due to flooding the carb. You allow it to sit and the excess gas goes out. make sence? So yeah allow it to sit for a bit and try to start it with the pecock set to on, full choke no accelleration.

    Have you pulled a spark plug out after trying to start it? Does it smell like gas? It should.

    You said it will start when you spray starting fluid in there, perhaps your fuel mixture is bad? Im sure you have new gas in the tank. I wouldnt mess around with the air mixture screws though untill your totally desperate, I think they're hidden in the body of the carb and you have to drill a lil hole out to get to it.

    If all else fails try cussing and throwing stuff. I see other people do it but so far it hasent gotten my bike to run.

    take a look at my post http://www.thegsresources.com/_forum...ic.php?t=18366

    Justin,
    GOOD LUCK

    Comment

      #3
      I hope that I don't end up in the same box as you guys. I'm at the same point with my rejetted and pod'ed carbs on my 81'gs750L.
      I will keep an eye here to see your solutions.

      Dm of mD

      Comment

        #4
        I JUST GOT MINE RUNNING!!!

        kinda, I rode it anyway..

        check it out http://www.thegsresources.com/_forum...ic.php?t=18366

        I basicly adjusted the float height to 22 mm and I put medicine ... lol no really medicine, like A&D ointment on the diaphram to help make a better seal. Started up right away.

        Comment

          #5
          The jet pointing to the air box is the pilot jet and the little hole on the right side is the main jet air pathage (sp?) The main Is in the middle of the carb in the bowl area. Found that out to today rejeting my carb with a stage 3 kit and pods. My bike an 80 Gs750E. I had to go to bikebandit and look at the carb diagram to make sure.

          Comment

            #6
            Got her running.

            Ok, just got her running tonight. I took the carbs back aprat and gave them a very thourough cleaning. They probably weren't this clean when they left the factory. Then, I used some oil on the diaphrams to ensure they were lubricated. adjusted the float eight. Patched everything up. I used silicone around the carb boots at the airbox to prevent air leaks, only a temporary fix, have newer boots coming. I put in a new air cleaner. I tried to start it, but wouldn;t start. used just a little starting fluid in the air box. She fired up. First time it has ran in 3 years. That was all it took. I let her run a little while and shut her off. She fired right back up, no need for starting fluid this time. Thanks to all. Everyone has been a huge help. I hope this will help the next person that follows in my shoes...

            Comment

              #7
              What I do sometime when trying to revive a bike that has sat for a long time is to Take the battery out of my car and hook it up with jumper cables To make sure that max voltage is available.

              Comment

                #8
                glad to hear you got it going dude, Im proud of ya. Mine crapped out, electrical problems this time I think, if it aint one thing its another isint it..

                Anyway, way to go dude, have fun.

                Justin

                Comment

                  #9
                  Awesome man! Congratulations. Once I clean my tank I can buy some starting fluid and try starting mine this week.


                  Dm of mD

                  Comment

                    #10
                    dont go nuts on that starting fluid though, I hear its murder on the engine

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