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    fuel trouble

    I have a 1982 GS650gl ..Its a standard gs engine. i have just finished the rebuild...finally got the electrical right. Now my problem is the carb gets fuel...so I know the petcock is okay. But it injects no fuel to the cylinders. I get good compression, good spark, just no fuel... the carb looks in good condition and the diaphrams are in good condition. Besides a total carb rebuild...does anyone have any obvious ideas? Any vaccume lines I may have forgotten.... Clymer does not do a good job explaining the fuel system.
    thanks
    -camaroman

    #2
    650 no fuel

    Hi, here are some ideas. The O rings between the carb boots and the motor shrink with age and cause leaking which won't pull fuel properly. Your jets may still be plugged. the clamps which tighten on the carb throats may not pull a seal and pull air and not fuel. Try running it with petcock on prime position, if it gets fuel this way the vacuum line from carbs to petcock may not be working, may have a leak. If it will run at all spray wd40 around the intakes when running, if engine revs up you have found the leaky problem.

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      #3
      I tried your suggestions with no avail. Thanks for the ideas though....I pulled the bowls apart...the main jets are not clogged... I ran it on prime...nothing still. I am not that familliar with the innerworkings of a carb. are there any other jets that could be clogged besides the main jet? I know on a car's carb..when you pull the throttle when the car is off...you can usually hear a spraying noise as the fuel is being injected....there is no such noise with the bike.
      thanks-
      -camaroman

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        #4
        Was there fuel in the bowls? on the BS carbs/ most motorcycles there is no accelerator pump, I would try some starting spray, if it try/ runs for a few seconds you need to check the carbs again/ if it doesn't you may need to check the ign.. It also will not run properly with out the airbox installed.
        To start when cold use full choke and NO throtle, with the bike in netural, and head light turned off so max voltage is available for starting

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          #5
          Besides the main jet there are several more. You need to checkout the carb cleanup series available on this site. It shows you where all the jets are located and how to clean them. It is very educational. If any jet anywhere is plugged, not to mention any little passage. it will run poorly at best. Also there is no fuel being pumped at any time. The pistons create a vacuum when going down and stil action sucks fuel in. That is why your intakes must be sealed.

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            #6
            clymer says to take the bowl off and check the jet under the floats to see if fuel passes freely.... if you tke the bowls off...the gas dumps out...how do you see if gas flows freely?

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              #7
              If you remove the bolt or the screw at the bottom of the bowl the gas will drain out more controled. Once you get the gas drained you can put gas into the carbs IF, the tank is higher than the carbs, and with the petcock in the prime position. Gas should flow from the bottoms of each carb. Catch the gas in a suitable container.

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                #8
                The gas is pulled up into the airstream by the pressure differential caused by the slide. Are you trying to run the carbs without the airbox attached? This will defeat the design of the carbs (CV) and it will seem like it isn't getting gas. A plugged pilot jet will also make it run this way. These carbs are made to run on the edge of leanness and it is crucial that everything is right with them.

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                  #9
                  How are the air jet screws supposed to be? Tightened down, or up half ?...

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                    #10
                    You're sure you're getting fuel to the carbs?? When you pull the bottom bowl plug does fuel come out??
                    After cranking the engine several revs...pull the spark plugs.
                    Are they wet?? With one plug removed and the other plug wires disconnected, crank the engine.
                    Do you smell any gas??

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                      #11
                      shebby,
                      yeah I pulled the bolts from the bottom of the bowls...and yes ther is lots of fuel in there.... I crank the engine....no smell of gas on the plugs or in the cylinders. I pulled the carb apart and performed cleaning as described on this site... Still nothing. How would having the air box off affect fuel spray?

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