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81 gs450 fuel leak

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    81 gs450 fuel leak

    See if i can stump you. I bought this bike about a week ago. when i bought it it leaked oil from somewhere around the shifter. they said they fixed it, and when i got it home, it still leaked a little, but not nearly as bad. i figured i'd open it up and change a gasket or somehitng, and i'd be over.
    I was looking at the leak the other day, and it looked like it had some gas in it. weird, i thought. how is gas getting in there? and no one say blown gasket. now, a couple days later, the leak is pretty bad, but it's almost all fuel. I can put a buck in the tank, and it'll all run out the bottom of the engine in about 5 minutes. the fuel looks like it's got some oil in it, but not much. so my questions are:
    how does gas even get down in there? do i have gas in my oil?
    which gaskets should i be looking at?
    and i guess, what should i do?
    Thanks

    #2
    Here's a guess for you. If you look at your oil it probably is overfull. Pull your gas line off from the carbs and the vacuum line as well from the carbs. In prime, gas should flow freely. Run or reserve, no gas should flow until you apply a vacuum (mouth works, just watch out for gas coming through!). If it leaks in run or reserve, petcock needs to be rebuilt. If you get a mouthful from the vacuum line, it needs to be rebuilt. If your oil is high drain oil and change, run for a while and change again. Gas and bearings/rings do not get along well. Bob

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      #3
      You might also want to check the float levels. I am battling the same problem you are. carbs should be back together tonite. sync'd this weekend, and popping wheelies by mon. :twisted:

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        #4
        float levels doesnt explain how gas came to be all the way down at the bottom of the engine, and coming out by the shifter. i just had the carbs apart yesterday, cleaned em up, and put em back on. i dont know

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          #5
          If your floats are misadjusted AND your petcock is leaking fuel then all that extra fuel runs into the crankcase via your cylinders.

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            #6
            I guess i see that. altho, if floats were stuck open, wouldnt fuel just run out of the overflow on the carbs?
            but here's why i think that's not it. i can start it, and it runs fine. then after about 5 seconds tons of gas comes pouring out the crank case at the bottom. if i shut it off, it leaks for a couple more seconds then stops.
            this is a difficult experiment to preform over and over because (1) i dont want my crankcase filled with fueil. its not good for it. and (2) every time i do it, i have to push it around the block to put more gas in it.

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              #7
              right. so i think you're on to something. i'm about to do that experement that bob suggested at the top there. but i'm a little confused about it. maybe someone can clarify.
              so i pull both lines off of the carbs. i apply a vacuum to the vacuum line, and i should get a mouthfull of gas, right? or do i apply a vacuum, and it should come out the main one? i think i just figured it out. is that right? and if i get a mouthful from the vacuum line, it's broke, cause it should come out the main one. right?

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                #8
                ok. here's where i am now (i'm getting the impression that i'm talking to myself here). i played with the petcock a little and found that it has already been rebuilt. the way i found that is that the reserve, off, and prime settings are all backward. so someone put the switch in the wrong housing, or something, then forgot to tell me. so apparently, i let it sit for several days in prime, and it filled the crank case with gas.

                so i drained it. filled it with oil. drove it around the block, and was sad to come home and see that it's still leaking. at least it's leaking oil now. so here's my new questions:

                does everything i've said already seem right?
                did i probly blow a gasket or seal when it was overfull of gas?
                what else should i do (besides fixing the leak) to make this all better?
                and what other advice, etc?

                thanks, guys. i'm learning alot here.
                [code]<html>[img]http&#58;//quantifier.org/red.jpg[/img]</html>[/code]

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                  #9
                  You're right about how the petcock works. Suck/gas flows, no suck/nogas. You should not have any in the vacuum line. I think you're on the right track about everything else. I don't know about the seal without looking at the bike. As far as how gas gets in the crankcase? It fills the intake and if an intake valve just happens to be open it will find it's way past the rings and down into the block. Pretty neat,huh? Bob

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