Announcement

Collapse
No announcement yet.

Ignition or Carburetion?

Collapse
X
Collapse
 
  • Page of 2
  • Filter
  • Time
  • Show
Clear All
new posts
Previous 1 2 template Next
    #1

    Ignition or Carburetion?

    Ok, so my 1982 GS1100GK has developed some issues.

    I posted earlier about my PCV hose coming off, and the subsequent stumbling and surging symptoms. I had put the hose back on and things were ok...kinda. But now it seems like the surging is getting worse and worse.

    It's surging under a load, in the 2500-3500 range. It feels a lot like what I'd expect an ignition failure to feel like; not a complete stumble, but a loss of power, like I'm pulling with 3 cylinders, then 4 again, then three, then four, and so on. Sometimes, but rarely, it will bog down completely - like it's two cylinders.

    Anyway, I went to try running it with the petcock switched to prime to try to rule out fuel starvation, and it didn't help at all. The bike had gotten wet at this point, so that might be a clue...Anyway, it ran like it was on two cylinders that time. After I forced it to idle with full choke for a while, it kicked back into normal running, but still not healthy.

    I went back to it a couple hours later and this time it fired right up. However, I decided to do a test and pull one of the plug wires. I got zapped a little, but that's ok...anyway, I didn't really notice a difference in the idle when I pulled #3. But #2 didn't seem to make a big difference either. Is this normal, or should a pulled plug really change the idle?

    Any thoughts on this problem? Thanks, GSR.
    Tags: None
    #2
    To me it sounds like it could be a plugged fuel filter in the tank. If it like my 1100e, there is a tall nylon filter in the tank that contains two pipes. If the filter is plugged up, the fuel will fill the carbs very slowly regardless of prime or not which would account for the occasional improvement. how fast does the fuel exit the tap if you disconnect the hose and put it to prime? If it is slow, the engine could be using the fuel faster than it can be replaced in the carbs bowls. I would also check the spark by removing the plugs and leaving them connected to their wires while grounding the body of the plug to the motor, crank it and watch for a good blue spark on all four. Yes, there should be a decernable difference in the rpm with the removal and replacment of each plug lead. If the engine is cold and just started, you can feel the exhaust pipes to see which ones get hot and which dont.

    Comment

      #3
      Have you rebuilt the carbs? Could be a sticking float/float needle.

      Brad tt

      Comment

        #4
        Originally posted by 3phase
        To me it sounds like it could be a plugged fuel filter in the tank. If it like my 1100e, there is a tall nylon filter in the tank that contains two pipes. If the filter is plugged up, the fuel will fill the carbs very slowly regardless of prime or not which would account for the occasional improvement.
        I guess I'd check that by pulling the petcock out? Am I going to have gasket issues with that?

        Originally posted by 3phase
        how fast does the fuel exit the tap if you disconnect the hose and put it to prime? If it is slow, the engine could be using the fuel faster than it can be replaced in the carbs bowls.
        How fast is fast enough? I'll check it before I remove the petcock or anything, but I don't really know what to look for.

        Brad, I haven't rebuilt the carbs. I did have a situation when the stator went south and the bike sat for about 4-5 months with no stabilizer in the gas. I sprayed the passages and the bowls with carb cleaner - but this was months ago. It's been running well since then, until this started.

        Now, I have synched the carbs since then and adjusted the idle mixture screws. I did this because my stock exhaust fell apart and I replaced it with slip-ons from JC Whitney. The slip-ons flowed a little more (I was running lean, I know that) so I richened the mix a little. The plugs were on the lighter side of cardboard brown. I didn't think much of it, it was nothing drastic, no jet or needle changes, and I don't think they'd be necessary since this system is so close to stock.

        Could a poor synch job (this was my second attempt at it, with a Morgan CarbTune) cause this problem?

        I am hesitant to believe it's a carb issue because of the rather sudden onset, and the way the engine power "flickers." On the other hand, I've never, ever had a coil go bad on me on any vehicle. Is there any kind of quick (even if its temporary) fix for a stuck float valve? Maybe spraying carb cleaner into the bowls or something?

        I did some electrical testing on my coils, and the primaries measure about 4.2 ohms. Is that spec? I can't seem to get continuity between my plug wires (2&3, 4&1), so I'm not sure how/if I can test the secondaries. Any help there?

        Comment

          #5
          Also, Brad...I like El Conquistador, that's some sweet pinstriping there. I looked at the ol' 750, too, and it prompted me to go look for the post about your wreck.

          What a story. What I take away from it is a reminder about why defensive driving is a must, though sometimes even that is not enough. Time to go check the brakes!

          Comment

            #6
            I have had very similar symptons when using a lower octane gasoline. My problem has gone away when I use 92 or 93 octane. My guess is you may have some bad gas or something is the carbs (maybe rust)..

            Comment

              #7
              You mentioned you noticed this when the bike got wet, and you mentioned getting a belt off the plug cap............could it be the breakdown of the 23 year old insulation on the leads and caps. I've seen this problem before and the symptoms are similar to a carburation problem. Check it out.

              Comment

                #8
                Funny you say that...I ruminated on this for a while and I think that 23 years and 32,000 miles might be too long for those plug wires. I think I will try Earl's method and cut them close to the coil and replace with automotive (resistorless) wires.

                Does anyone know the rationale for the resistors, anyway? And will I want to change my spark plug gap if I ditch the resistor?

                Comment

                  #9
                  From your comment that you were "zapped" when removing plug wires, I think you have a "leak" and if the bike gets wet, your wiring is grounding out.
                  One way to check this is to put the bike in the garage at night, remove the gas tank. Run a long fuel line from the tank to the bike so you can run the bike. Take a spray bottle of water and spray a little mist around the plug wires and coil area. Then start the bike in the dark and turn the headlight off. If there are electrical leaks, you will see "little blue worms" all over your bike. :-)

                  I would still replace the plug wires and caps simply because of age though.

                  To check resistance on the coil secondary, put the multimeter probes into the metal clip inside the 1 and 4 caps to test the left coil. resistance between the caps should be 30 to 40k on the average. (coils unpowered for this test) Meter set to ohms 200k scale.

                  Earl


                  Originally posted by trnpkroadwarrior1019
                  Funny you say that...I ruminated on this for a while and I think that 23 years and 32,000 miles might be too long for those plug wires. I think I will try Earl's method and cut them close to the coil and replace with automotive (resistorless) wires.

                  Does anyone know the rationale for the resistors, anyway? And will I want to change my spark plug gap if I ditch the resistor?
                  Komorebi-The light filtering through the trees.

                  I would rather sit on a pumpkin and have it all to myself than be crowded on a velvet cushion. H.D.T.

                  Comment

                    #10
                    Is there a kink in the fuel line?

                    Look under the tanks and make sure the fuel hose is not bent over. The lines are only 1/4 inch and a bent fuel line will starve them out.
                    1981 GS650G , all the bike you need
                    1980 GS1000G Power corrupts, and absolute power corrupts absolutely

                    Comment

                      #11
                      Nah, no kinks. I checked that right away...the fuel line has this handy spring thing wrapped around it anyway that I think helps prevent that from happening?

                      Thanks for the help, Earl. I will report back once new wires are on. It's finals week here in Shepherdstown and it's got me a bit distracted from my baby.

                      -Dom

                      Comment

                        #12
                        Epilogue

                        Well, it was indeed the wires & boots that were the cause of my worry. I removed the boots from the wires and shook them by my ear, and sure enough you could hear the resistor rattling around in there, no longer snugly fit but worn, chipped, etc.

                        I took them apart for the sake of curiousity and to see if a rebuild was possible, but I ultimately decided there was no valid reason that plug boots should have 4 or 5 distinct parts unto themselves, and put them away in the "Stock GK Souveneir Jar" where all my old parts go just in case my fixes turn out to be faulty.

                        I could have replaced them with new stock boots - but at a princely sum of $15 each from BB. Instead, I went out and got new plug wires at the auto parts store. The only DIY set they made was for a V8, but I figure this way I have an extra set.

                        The real fun, though, was splicing them on. They didn't have copper wires at the store, you see, so I bought the graphite wires. And everybody and their grandmother told me this would never work, you'll never get it to run like that, blah blah blah...But you know, they use metal prongs to secure the graphite wires to the distributor cap and the plug itself, so the graphite obviously conducts to metal. With that in mind, I stripped back the insulation on about 1/2 inch on each wire, wrapped the copper around the graphite core, taped, RTV'd, shrink wrapped, and taped again. Then I did it three more times, put the coils on the bike, and ka-vroom, she started right up and rode like a new machine.

                        All the old ails are gone, and my GK and I are back on the road as happy as ever. Thanks to all of you who helped, especially Earl who took the time to answer some PMs about this. I hope I can make it to the Southeastern Rally so I can meet some of you guys.

                        Happy riding, and keep the rubber side down!

                        -Dom

                        Comment

                          #13
                          Great, I diagnose your problem and you thank earl..........thanks.

                          Comment

                            #14
                            Originally posted by Guy
                            Great, I diagnose your problem and you thank earl..........thanks.
                            Get used to it my man!
                            You nailed it though!
                            And on the seventh day,after resting from all that he had done,God went for a ride on his GS!
                            Upon seeing that it was good, he went out again on his ZX14! But just a little bit faster!

                            Comment

                              #15
                              Don't mind me, just blowin' off a bit of steam today!

                              Comment

                              Previous 1 2 template Next
                              Working...
                              X