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#1 cylinder dead, stumped

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    #1

    #1 cylinder dead, stumped

    Ok so I have a 1981 GS850G that I purchased out of a long storage. 23k miles
    New plugs
    New air filter
    New cylinder head carb boots
    New coils
    Carbs rebuilt by one of our GS members
    Valves adjusted
    Compression 145-150 across the board.
    I cannot get the #1 cylinder to fire. I have switched plugs, coils and wires and #1 stays dead. RPM's do not change when removing plug wire at idle or at @2500 rpm . Idle does not change when adjusting the air screw, heck I took it right out with no effect. Rpms do not change when giving the intake boot a squirt of carb clean with air filter door removed. The boots inside the air box have been chewed but I cant get it to pick up #1 even with the airbox off.
    I am stumped and frustrated at this point and just had to walk away for a bit.
    Any ideas would be welcome at this point.
    Tags: None
    #2
    have you taken plug 1 out and held it against the engine and cranked it to see if theres a spark..and if so is it pretty bright or weak and dim???
    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

      #3
      I have. The spark seems pretty decent. I went so far as to take the wires from #4 and swap it with #1 and the problem stays at #1.
      The only other thing I haven't done is remove the header pipe and look for a restriction, although my experience with exhaust restriction makes plugs foul quickly. Maybe tonight.

      Comment

        #4
        Remove the drain screw on carb and make sure you are getting fuel, may have a stuck only valve. Or just tap the carb with a screw driver handle. Seen it happen before
        1984 GS1100GK newest addition to the heard
        80 GS 1000gt- most favorite ride love this bike
        1978 GS1000E- Known as "RoadKill" , Finished :D
        83 gs750ed- first new purchase
        85 EX500- vintage track weapon
        1958Ducati 98 Tourismo
        “Remember When in doubt use full throttle, It may not improve the situation ,but it will end the suspense ,
        If it isn't going to make it faster or safer it isn't worth doing

        Comment

          #5
          Any difference if you use the choke? Might be something plugging the pilot jet, using choke bypasses that.
          If you're not living on the edge, you're taking up too much space.

          Comment

            #6
            The bowls have fuel. Pilot jet looks good. Pulling the choke seems to have no effect. I might replace the pilots anyway as i have a set from my old 850.
            Thanks

            Comment

              #7
              Put your hand over that carb and crank it to see how much suction it feels like as compared to another one thats getting hot. But you stated so real good compression numbers though...HMMM.
              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

                #8
                Ok, I put the carbs back on, double checked my coil wiring and removed the #1 exhaust pipe---no change.
                I then disconnected the choke on the #1 carb so I could operate it separate from the other 3. At idle, when I pull the choke on #1 ONLY, cylinder starts to fire, the idle rises @1k rpms, cylinder exhaust and head temps rise to match the other 3. I would assume this means the cylinder is LEAN. BUT I would assume by placing my hand over the carb throat at idle I could get the same effect---but I don't, it floods.
                Not sure what this means, I will have to study my carb diagram again after dinner...............

                Comment

                  #9
                  It will flood easily with your hand over the carb...use a shop rag or a few layers of Tshirt for restriction. Im thinking maybe the #1 butterfly isnt as open as #2 as they are on the same adjuster screw. May have to fiddle with the sync screw a little bit each way to see if it opens the butterfly and she catches. Ive seen it happen even with a real close bench sync..little more tweeking and magic.
                  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

                    #10
                    The thing is that cylinder never comes in even after idle unless that choke is pulled. I did a vacuum synch and it seemed all was well. ???
                    I am not gong to get much more done on it tonight, or tomorrow for that matter. Daughter hit a deer with the wife's car and I got to fix that also. It never ends......

                    Comment

                      #11
                      Sounds like the pilot / idle jet passages are blocked.
                      Current:
                      Z1300A5 Locomotive (swapped my Intruder for it), GS450 Cafe Project (might never finish it....), XT500 Commuter (I know - it's a Yamaha :eek:)

                      Past:
                      VL1500 Intruder (swapped for Z1300), ZX9R Streetfighter (lets face it - too fast....), 1984 GSX750EF, 1984 GSX1100EF (AKA GS1150)
                      And a bunch of other crap Yamahas....

                      Comment

                        #12
                        Possibly, but all 4 were dipped 24 hrs and all 4 got the same rinse, carb spray, and air in very copious amounts...I know because I did them. I Pmed Rich saying if he wanted to send that body back I would gladly dip it again and assume all his shipping costs and I myself am at a loss as to why too.

                        So, Rich, if you want to send that body back I stand behind the work 100%. Its quite possible that body had way more than the others but the spray and air flowed nicely. In any case Just PM me for the address again if you dont still have it and I will redo it. let me kn ow.
                        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

                          #13
                          I am wondering if the float/float level could be the culprit? I know the pilot jets are clean, needs to double check the passage.
                          Thanks Chuck, you are a man of your word for sure. I will try to get to this late tonight if possible.
                          Last edited by Guest; 08-23-2017, 10:50 AM.

                          Comment

                            #14
                            Float level won't cause a cylinder not to fire at all. It's something else.
                            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

                              #15
                              But low float level would cause a no fuel situation, correct? Or is the main jet/ pilot jet so far in the bowl it would be impossible to starve it for fuel? It seems The choke circuit pulls fuel from the bottom of the bowl.
                              Thanks for any insight.

                              Comment

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