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please help. first project bike gs750 1978 leaking oil from exhaust and intake

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    #1

    please help. first project bike gs750 1978 leaking oil from exhaust and intake

    Hi I'm new to the forums and have been doing a good deal of reading on here but can't find an answer.


    my gs750 leaks oil from the far left exhaust manifold (small steady drip) can't figure out why, i took it for a ride today and after about 2 miles i looked down and it started spraying oil everywhere, out the exhaust and the carburetor(still far left side)
    oil may have been leaking from other places but it was hard to tell as i pulled over the bike.

    as the bike warmed up the oil leaked more and the throttle hesitated more and more until it died. felt like a it was losing compression.



    please help! thanks
    Tags: carburator, exsaust, gs750, leaking, oil
    #2
    Oil from the Carb?

    Look at the underside of the motor and the side covers for leaks. Sometimes an oil leak that looks like its coming 'from" an exhaust header, is actually coming from somewhere else and just dripping and flowing back along it.

    Pull the #1 plug. is it oil or black gunk covered? blown valve guide seal.

    Comment

      #3
      Originally posted by JamesWhut? View Post
      Oil from the Carb?

      Look at the underside of the motor and the side covers for leaks. Sometimes an oil leak that looks like its coming 'from" an exhaust header, is actually coming from somewhere else and just dripping and flowing back along it.

      Pull the #1 plug. is it oil or black gunk covered? blown valve guide seal.



      I just replaced all the plugs today, black gunk covered for sure.

      Comment

        #4
        Needs a top end rebuild.

        Comment

          #5
          Check the oil. take cap off and smell for gassy odor. If the petcock failed it will fill the crankcase with gas and then the lubrication for the engine is gone. Dont even start it till you are 1000% sure it isnt full of gas. Drain the oil and start over with fresh is what I would do. If more than 3 1/2 QTs comes out when you drain the oil there is your problem.

          An over full crankcase forces the oil / gas slop to go somewhere and usually it either out the exhaust or thru the breather cover and runs down into the airbox from the breather tube. Im leaning at a petcock failure as my first suspect...especially if it wasnt that way before and suddenly it has happened.
          Last edited by chuck hahn; 05-15-2016, 09:20 AM.
          MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
          1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

          NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


          I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

          Comment

            #6
            Originally posted by chuck hahn View Post
            Check the oil. take cap off and smell for gassy odor. If the petcock failed it will fill the crankcase with gas and then the lubrication for the engine is gone. Dont even start it till you are 1000% sure it isnt full of gas. Drain the oil and start over with fresh is what I would do. If more than 3 1/2 QTs comes out when you drain the oil there is your problem.

            An over full crankcase forces the oil / gas slop to go somewhere and usually it either out the exhaust or thru the breather cover and runs down into the airbox from the breather tube. Im leaning at a petcock failure as my first suspect...especially if it wasnt that way before and suddenly it has happened.
            Chuck, these are VM carbs, if the petcock failed wouldn't the gas just flow out the overflow tubes?
            -Mal

            "The only reason for time is so that everything doesn't happen at once." - B. Banzai
            ___________

            78 GS750E

            Comment

              #7
              Probably just the valve cover gasket for the oil leaks.

              Get some water based degreaser, spray engine down, let stand for awhile, rinse with water. Allow to dry, start bike, look for leaks at top of engine.

              Have you done an oil change yet? If not, as Chuck mentioned, do that before you run it.

              Report back the results
              1978 Gs1085 compliments of Popy Yosh, Bandit 1200 wheels and front end, VM33 Smoothbores, Yosh exhaust, braced frame, ported polished head :cool:
              1983 Gs1100ESD, rebuild finished! Body paintwork happening winter 2017:D

              I would rather trust my bike to a technician that reads the service manual than some backyardigan that THINKS HE KNOWS how to fix things.

              Comment

                #8
                All my bikes have VMs and when my 78 1000C failed it had almost a gallon of fuel mixed in with the oil. I thought the drain pan was gonna overflow. What clued me off was the fuel gauge actually. I hit the key and the fuel level was oddly way to low from what I remembered from the last ride so I smelled the filler hole. No fuel from the carbs, airbox or under the bike at all. Most likely the fuel ran down the vacuum tube off carb 3.
                Last edited by chuck hahn; 05-15-2016, 10:52 AM.
                MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
                1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

                NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


                I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

                Comment

                  #9
                  Originally posted by chuck hahn View Post
                  Check the oil. take cap off and smell for gassy odor. If the petcock failed it will fill the crankcase with gas and then the lubrication for the engine is gone. Dont even start it till you are 1000% sure it isnt full of gas. Drain the oil and start over with fresh is what I would do. If more than 3 1/2 QTs comes out when you drain the oil there is your problem.

                  An over full crankcase forces the oil / gas slop to go somewhere and usually it either out the exhaust or thru the breather cover and runs down into the airbox from the breather tube. Im leaning at a petcock failure as my first suspect...especially if it wasnt that way before and suddenly it has happened.



                  not smelling any gas in the oil.

                  it WAS happening before just not to this extent, there has always been a small oil drip from from the exhaust manifold. it sprayed oil after taking it for a first ride.

                  Comment

                    #10
                    Originally posted by Fjbj40 View Post
                    Probably just the valve cover gasket for the oil leaks. Get some water based degreaser, spray engine down, let stand for awhile, rinse with water. Allow to dry, start bike, look for leaks at top of engine. Have you done an oil change yet? If not, as Chuck mentioned, do that before you run it. Report back the results

                    already replaced valve cover gasket and changed the oil

                    Comment

                      #11
                      Obviously the first step is to clean off the engine so you can se where it's leaking from. Do as Fjbj40 says, and find the leaks. Maybe it's leaking everywhere, maybe one big leak and swirling around. Maybe the whole thing needs to come apart, maybe not. It's hard to tell from here.
                      http://img.photobucket.com/albums/v5...tatesMap-1.jpg

                      Life is too short to ride an L.

                      Comment

                        #12
                        Originally posted by tkent02 View Post
                        Obviously the first step is to clean off the engine so you can se where it's leaking from. Do as Fjbj40 says, and find the leaks. Maybe it's leaking everywhere, maybe one big leak and swirling around. Maybe the whole thing needs to come apart, maybe not. It's hard to tell from here.



                        will do! also doing a compression test on the cylinders, will post results

                        Comment

                          #13
                          update:
                          compression came in at around 115 psi for pretty much every cylinder.

                          i cleaned off the engine, oil must be coming from the valve cover but leaking somewhere i can't get a view of.

                          i also forgot to mention that oil shot out of the breather house last time i went for a ride..



                          thanks for all the replies so far
                          Last edited by Guest; 05-16-2016, 09:38 PM.

                          Comment

                            #14
                            How full is the oil in the crankcase? Above the window or just right?
                            http://img.photobucket.com/albums/v5...tatesMap-1.jpg

                            Life is too short to ride an L.

                            Comment

                              #15
                              Originally posted by tkent02 View Post
                              How full is the oil in the crankcase? Above the window or just right?

                              window seems like its fogged over but looking down into it, oil seems higher than the window.

                              would that cause high compression and oil to erupt out of the breather hose?

                              Comment

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