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    Carb leaking petrol and unable to kickstart.

    Hey All,

    I just followed the carb rebuild kit that I found here for the VM carbs. Great guide so thanks for that. I replaced all the o rings wit the ones from the site siggested in the guide. all fit perfectly. I didn have any gasket material so went to the local auto store and made my own by tracing the old gaskets that were in a pretty sorry state but still good enough to copy. cleaned everything put it all back together.

    Filled with petrol, and tried to kickstart the thing as my electric start does not work ( i'm still trying to find ou the reason for that ) I have the ignition on, rear light is on, brand new battery, try to kickstart it and nothing happens...... then after I got tired enough and set down next to the bike to relax, I noticed that the sides of the carb bowls have petrol all over them and it looks like its coming from the space beetwen the carb and the bowl, I guess the gaskets I made are not good enough. Anyone know what material I would need to make them out of. At the moment I used gasket paper that is the same thickness if not a little thicker to the gaskets that were on the carbs. Should I be using something else ? Any ideas would be great.

    #2
    It's not the gaskets that are at fault - they're not designed to hold back fuel if the bowls are brimming, just stop it coming out as it slops back and forth when accelerating / braking.

    First thing to check is float height as per the manual. If that is ok then check the float valves and their seats - use a magnifying glass. Any imperfection will let fuel past the valve and she'll leak.

    As for the kickstart is the bike just not starting or is it jammed?
    79 GS1000S
    79 GS1000S (another one)
    80 GSX750
    80 GS550
    80 CB650 cafe racer
    75 PC50 - the one with OHV and pedals...
    75 TS100 - being ridden (suicidally) by my father

    Comment


      #3
      I set the float height to 24mm as per the carb rebuild guide. Ill double check the float valves and their seats as per your suggestions thanks.

      She just wont kickstart, not jammed, just doesnt do it. This is my first kick start bike so hopefully im doing it right. ignition on, fuel getting to carbies and kick start yeah ?

      Might pay to let everyone know that i just bought the bike and havent heard it run before although PO is adamant that it ran a year ago when he bought it.

      I'm thinking of buing new coils, HT leads, regulator/rectifier and starter solenoid and trying to start it that way. Just wanted to clean carbs out cause everyone says to clean those first, they were all gunked up inside so im glad i did.

      Comment


        #4
        It'll be the float valves or seats (or both) then.

        Have you checked that she's sparking at the plugs? She should start easily on the kicker if she has fuel and spark.

        Plus don't go shelling out on all that new electrical stuff without testing each component beforehand. The guys on hear can talk you through all the tests or you could search for them.

        And before the multiude chip in - check your valve clearances. Tight valves = hard starting.
        79 GS1000S
        79 GS1000S (another one)
        80 GSX750
        80 GS550
        80 CB650 cafe racer
        75 PC50 - the one with OHV and pedals...
        75 TS100 - being ridden (suicidally) by my father

        Comment


          #5
          It may be badly flooded from all the fuel. If its a kick start bike, it should have come with slide carbs. Don't those have overflow ports on them?
          sigpic Too old, too many bikes, too many cars, too many things

          Comment


            #6
            Originally posted by 850 Combat View Post
            Don't those have overflow ports on them?
            They do but they are higher than the bowl gasket. Low enough though to stop fuel getting in the gearbox (most of the time....).
            79 GS1000S
            79 GS1000S (another one)
            80 GSX750
            80 GS550
            80 CB650 cafe racer
            75 PC50 - the one with OHV and pedals...
            75 TS100 - being ridden (suicidally) by my father

            Comment


              #7
              Did you activate the choke before kicking? Turn the fuel valve to Prime to fill the bowls?

              I've made float bowl gaskets several times before. It's easy enough, just make sure to use fuel safe gasket paper available at auto parts stores.

              The leakage as described could be either a bad gasket, but most likely the float valve is not holding back the fuel like it should. Rust in the gas tank often plays havoc with fuel valves so that's another thing to check.

              Good luck
              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


                #8
                Originally posted by Koff View Post
                I set the float height to 24mm as per the carb rebuild guide. Ill double check the float valves and their seats as per your suggestions thanks.

                She just wont kickstart, not jammed, just doesnt do it. This is my first kick start bike so hopefully im doing it right. ignition on, fuel getting to carbies and kick start yeah ?

                Might pay to let everyone know that i just bought the bike and havent heard it run before although PO is adamant that it ran a year ago when he bought it.

                I'm thinking of buing new coils, HT leads, regulator/rectifier and starter solenoid and trying to start it that way. Just wanted to clean carbs out cause everyone says to clean those first, they were all gunked up inside so im glad i did.
                You need to be more methodical

                1. Is there spark? Blue/white spark? It probably needs new points and condensors. This is the most common problem with bikes that have sat for a while

                2. Is gas getting to the plugs? aka are they wet?
                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


                  #9
                  Check spark before jumping to any conclusions. Since you're kick only, a friend might come in handy.


                  I can't find the thread right now, but one problem posted about the carbs overflowing turned out to be one side of the float was tweaked and rubbing the edge of the float bowl. When I've had a sticky float though it's been a free flowing situation, not your seeping leak you've mentioned. Sounds to me like you might need some different gasket material or the needles need to be replaced as already pointed out.

                  As for kick start, I like to turn the choke on and give it one or two priming kicks before turning on the ignition. Also, if your settings for air, fuel, and idle screws aren't in the right ball park it can be extra stubborn on the first start when refreshing a bike like this.

                  Comment


                    #10
                    as stated above^^ make sure its getting fuel.
                    and turn off your lights if your bike has the option, which it should if your using factory controls.
                    it makes mine easier to kickstart with a low,really cold, or dead battery.

                    Comment


                      #11
                      With regard to spark. If it looks weak or is non existant then first change the plug caps. Often, over time, they wear out/ break, generally become more resistant to the flow of the electricity. They are relatively cheap ($6/7) and screw on to the leads. Start with those. Twice in the past I have found this to be a "no spark/weak spark" issue.

                      With the float bowl gaskets, a neat little trick to make them more resistant to fuel leak while making them reuseable is to smear them (both sides) with a little axle grease. They will seal better and next time you open the bowls they'll peel off and be ready to reuse.

                      The leaking carbs could also be due to the vacuum petcock not shutting off and allowing fuel to run continuously ( as in the prime position). A common problem with these petcocks. a petcock rebuild or better yet a new pcock might be in order.

                      Good luck with it and let us know when you get her running.

                      Cheers,
                      Spyug

                      Comment


                        #12
                        Thanks for all the suggestions. I didnt use the tank or petcock as the tank had surface rust in it so I just used a clean bottle and put the fuel line into the lid and let gravity flow directly to that and the vacum line i sealed by putting a golf tee into it as suggested on a tank topic on this site. im cleaning out the tank atm, so once i get rid of the surface rust Ill use it and the petcock. Petcock seems to be working as when I had the tank off the bike, it would flow freely on prime but not on 'on' or 'reserve'. I bought clear fuel lines as the old ones were pretty perished so I can see the fuel now as well to make sure its all flowing as it should.

                        I'll double check the sparks tonight, I bought new sparkplugs as the old ones had a lot of carbon build up on them and just looked old. The new sparkplugs however do not fit into the old caps cause of different ends so will need new caps now. It's never ending. But the missus seems to be ok with it all. I'm an IT Manager so anytime I'm away from my phone, ipad or PC shes happy about it.

                        Once again, thanks for all the suggestions. Just of the top of someones head, how do i check if the coils are ok ??? I know I need to check resistance in them but across which two points ?

                        Comment


                          #13
                          Normally the plugs come with a removable outer piece. You normally leave it on for automotive apps and unscrew it for motorcycle applications. Try unscrewing it first.

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