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    Looking for some input

    Hey guys looking for some input...

    I have a "bone stock" 79 GS 550L that I have perfomed the following on:

    1.) Cleaned and Cremed the gas tank.
    2.) Cleaned the gas cap vent.
    3.) Cleaned the petcock and ensured that it worked.
    Replaced the fuel lines (petcock and main feed) and fuel filter
    4.) Adjusted the valves shimed to spec.
    5.) Cleaned the airbox and the air filter and re oiled the filter with 10-40
    6.) Replaced the plugs and gapped to spec.
    7.) Filed flat and adjusted the "Kukosan" points to spec around .014 I believe (they still have about 1mm of material on each point) and adjusted the timing using a test light until the light just barely went out on both points. The spark when the points separte is very minimal so i think the condensors are ok.
    8.) Checked the resistance on the the primary and secondary side of each coil. I cant remember what they measured, but they were with in the specs given by Earl.
    9.) The compression is about 110-120 per cylinder (with out the clutch pulled in).
    10.) The battery has a full charge of about 12.5-13volts and the water level is good. The charging system seems to be working ok.
    11.) Replaced the intake o rings and applied a small amout of high temp grease. Also applied a small amount of grease on the o rings on the inside of the intake boots on the carb side. Replaced the hardware with socket heads. Ensured that all of the hose clamps were tight and round to seal the airbox side and head side of the carbs. boots are in good condition no cracks or holes.
    12.) Dismantled and cleaned the *@%^$*@%^$*@%^$*@%^$ out of the carbs three times using a small wire to clear all of the jets. Let the carbs sit in carb cleaner (chemtool) over night and then blew all of the components out with compessed air. When I cleaned the carbs I didnt mess with the fuel pilot screw located near the bottom of the bowl however I am not the original owner and there is nothing to indicate that it hasnt been messed with by the previous owner, i.e., if there was yellow paint there originally it isnt there now nor before I cleaned them. I made sure that the fuel pilot needles were not sticking through the inside wall of the carb and made sure that the passages were clear by blowing carb cleaner and compressed air through the idle circuit of the carb. I adjsuted the air mixture screw to 2 turns out and replaced the o rings on the needle. I didnt mess with the slide adjustment assembly, i just cleaned it well and then reinstalled it into the carb body. The needle and seat does not have any wear from extended contact and the floats have all been set to precisely 26mm. the needle spring seems to be functional and the floats do not have any cracks or holes in them - they are also straight and not bent up. I also reduced the two upper vent lines on the carbs to about 3 inches. Everybody else was doing it so i thought i would give it a try
    13.) I have sprayed the intake area down with a ton of water to try and find a vacuum leak and have found nothing - (I do not want to use wd-40 or any other oil so please dont suggest this) I also sprayed the head area down with water to check for head gasket leaks - also there was no increase in RPM.
    14.) I have not synced the carbs with a merc stick because I am afraid of sucking mercury into the motor due to it sometimes increasing to around 3000 and higher rpm from idle for no apparent reason. I have tried to adjust the mixture screws by the higher rpm method but have not had any sucess since I cant hear any significant change in rpm in either direction. This occurs even when trying to adjust each side of the motor at a time. So i set them back to 2 full turns out on each carb.

    Sooo....

    The bike runs and runs great going down the road, but I have to regulate the gas during cranking when its cold, and it only fires on two or three cylinders when I first crank it. As I reduce the choke which I have to do immediately or it will foul out the plugs it starts to fire on all four, but i still have to regulate the gas, if I let off it will die. Once I start off after two or three minutes of running and the choke half way between on and off, it sputters a little once in a while and backfires through the exhaust especially when I let out of the gas. Once its warmed up it runs great going down the road (choke completely off). Sometimes it will idle smooth as silk. Others or 50% of the time it will have an erratic idle. Somtimes when I come to a stop light it will idle low 1200rpm and smooth for 5 minitues, others it will rev to around 3000-5000rpm with no throttle. This will occur until I let out the clutch a little and bog it down. Then it will idle at around 1200rpm and continue that way a period of time and then try and rev up again.

    The plugs seem to be burning ok but i have never been impressed with their spark - In my opinion it sucks but this it the first points style ignition system I have worked with so I have nothing to compare it to.

    I am wondering if the ignition system is the root of my problem, and if that is the case the Kukosan style points are so expensive that i might as well convert over to an electronic ignition. If that is the case what is the best and most cost effective method of converting the bike over to electronic ignition. Also what coils will work on this bike that are used on other late model bikes (can i just get a coil that has the same primary and secondary resistance or is it more involved than that?) What other than an intake leak would make the engine rev up with no throttle and what are the symptoms of the carbs not being synced with a flow meter or mercury stick.

    On another note can you hook the bike up to a battery charger (2 or 6 amp) during cranking to help reduce the strain on the battery or will this hurt the charging system.

    HEEEELPPPP!!!!!! I am going insane 8O

    #2
    The little critters can drive you insane.

    I had similar symptoms on my 1100. I had cleaned the #### out of the carbs too. So I thought. I finally broke down and tore into them again. I found that the pilot jets or low speed jets (not the needles) were still plugged on the bottom. There is a tiny (more like microscopic) hole in the bottom of these jets that I missed. I used one strand of wire out of a piece of 18 AWG hookup wire to clean it out. After putting it back together, it ran fine.

    Comment


      #3
      same experience with the pilot (idle) jet. used a wire from a wire brush to clear it. had similar symptoms.

      don't use a charger to crank it. bad juju. don't ever charge at more than two amps either.

      points ignitions properly working will create a big blue spark. check voltage to your coils first, and possibly replace the caps, they should be cheap , like 3.50 each or so for NGK caps. file the points and set em to spec.

      carb synch makes a big difference on these bikes, that could account for erratic idle, adjust the valves and then synch the carbs. dont worry about sucking the mercury in, I don't think your engine could ever create the vacuum needed to pull it all the way to the engine. I had mine over three grand with the sticks on and it didn't pull the mercury even halfway up the sticks. never got anywhere near where it coulda been a problem

      Comment


        #4
        LW,

        What do you mean by the caps? These coils seem to have the plug wires moulded into them. they do not seem to be replaceable.

        Also what is the ignitor? I have seen theis mentioned on this forum but i am not familiar with what it is? Is this something off of the later models that had electronic ignitions?

        I think that the pilot jets are cleaned. I used a wire brush wire to clean out all of the jets very thoroughly - however I fear that I may have to tear them back down again before this is all over just to check it all once more.

        the valves have all been shimed to spec.

        Thanks Guys,

        Keep it coming...

        Comment


          #5
          Originally posted by Birdman
          LW,

          What do you mean by the caps? These coils seem to have the plug wires moulded into them. they do not seem to be replaceable.

          Also what is the ignitor? I have seen theis mentioned on this forum but i am not familiar with what it is? Is this something off of the later models that had electronic ignitions?

          I think that the pilot jets are cleaned. I used a wire brush wire to clean out all of the jets very thoroughly - however I fear that I may have to tear them back down again before this is all over just to check it all once more.

          the valves have all been shimed to spec.

          Thanks Guys,

          Keep it coming...
          Just make sure that when you clean the pilot jets that you clean the little hole in the bottom.

          Comment


            #6
            I'll make sure of it.

            Thanks mixongw.

            btw how do you create the quote box to comment on what someone said

            Comment


              #7
              Originally posted by Birdman
              I'll make sure of it.

              Thanks mixongw.

              btw how do you create the quote box to comment on what someone said
              Nevermind - i just figured it out

              Comment


                #8
                Anybody else?

                before I set this thing on fire and drag it down the road behind the dodge

                Dont worry ill post video if i do :twisted:

                Comment


                  #9
                  the caps are the resistor caps at the end of the wire, they just unscrew off the wire. sometimes just triming an 1/4 inch off the end of the wire is enough.

                  the wire is indeed epoxied to the coil, and is "non replaceable" unless you want a small project.

                  have you verified good power to the coils? I know mine only showed 10 volts when the battery was nearer 13 volts. remember a weak spark in the atmosphere is no spark under pressure ( higher cylinder pressures require a stronger spark)

                  so if its lame like you suggest its likely barely firing. and that would make the plugs easy to foul. check every connector anywhere near your points, and follow the wires, make sure any connectors are clean, and theres no resistance anywhere. you should be able to get a big blue spark.

                  if the points look ok and the spark sucks try new capacitors. make sure there is a little lube on the points cam as well or the points will jump.

                  spark is stronger on the break than on the make, but by your description you knew that, sounds like you set em right.

                  Comment


                    #10
                    Thanks LW,

                    I'll check it out on sunday night.

                    Its time to head to the woods and hunt some Whitetails :twisted:

                    Deer that is...

                    Later.

                    Comment


                      #11
                      Originally posted by LW_Icarus
                      the caps are the resistor caps at the end of the wire, they just unscrew off the wire. sometimes just triming an 1/4 inch off the end of the wire is enough.

                      the wire is indeed epoxied to the coil, and is "non replaceable" unless you want a small project.

                      have you verified good power to the coils? I know mine only showed 10 volts when the battery was nearer 13 volts. remember a weak spark in the atmosphere is no spark under pressure ( higher cylinder pressures require a stronger spark)
                      so if its lame like you suggest its likely barely firing. and that would make the plugs easy to foul. check every connector anywhere near your points, and follow the wires, make sure any connectors are clean, and theres no resistance anywhere. you should be able to get a big blue spark.

                      if the points look ok and the spark sucks try new capacitors. make sure there is a little lube on the points cam as well or the points will jump.

                      spark is stronger on the break than on the make, but by your description you knew that, sounds like you set em right.
                      FYI

                      A spark plug will discharge the potential generated by the coil with an arc that is hotter and wider in high pressure than at atmospheric pressure. There are more ionizing particles and they are closer together under pressure.

                      Comment


                        #12
                        well, when I worked in a fabrication/engine shop it was explained to me like this- when the cylinder pressure is high, there are more molecules for the spark to travel through,and these essentially act to insulate the electrodes. the spark would actually have the easiest time bridging the gap in a complete vacuum. and so a 13.5 to 1 compression ratio required a considerably more robust ignition system

                        Ive looked for papers documenting this and havent found em yet. but if it were easier to make a spark under extreme pressure, companies like accel would be hurtin, cause as you built a more radical race engine, your coil requirements would reduce. only time youd need more is if you were gonna spin a higher rpm.

                        I did find this from NGK:
                        Since the gap size has a direct affect on the spark plug's tip temperature
                        and on the voltage necessary to ionize (light) the air/fuel mixture, careful attention is required. While it is a popular misconception that plugs are pre-gapped from the factory, the fact remains that the gap must be adjusted for the vehicle that the spark plug is intended for. Those with modified engines must remember that a modified engine with higher compression or forced induction will typically require a smaller gap settings (to ensure ignitability
                        in these denser air/fuel mixtures). As a rule, the more power you are making, the smaller the gap you will need.

                        that looks like its tougher to bridge the gap, and I need to move the electrodes closer in a hi compression engine?

                        Comment


                          #13
                          I believe the reasoning that says higher compression engines need a smaller gap is due to the increased heat of compression, not density of charge, as NGK says. It's a proven fact that more voltage or a smaller gap is needed as air, or in this case, fuel/air mixture temperature increases.

                          Comment


                            #14
                            My last post on this prticular topic, as its pretty irrelevant, but this is from another source
                            Something many do not know, is that with Higher Compression ratios and Superchargers as well as Nitrous, in many cases smaller spark plug gaps must be used as well as the use of a much hotter ignition system (see above). These higher cylinder pressures require more energy to jump the spark plug gap.
                            from http://www.centuryperformance.com/spark.asp

                            I dont think NGK is wrong about spark plugs and cylinder pressures, and I don't doubt my teachers as they've not steered me wrong before. believe what ya want, but Ive been in the automotive business since before I could drive em. there are few things I know better than the whys and hows of an internal combustion engine.

                            Im not trying to start a war, just doing my part to stop the misinformation.

                            Comment


                              #15
                              Originally posted by LW_Icarus
                              My last post on this prticular topic, as its pretty irrelevant, but this is from another source
                              Something many do not know, is that with Higher Compression ratios and Superchargers as well as Nitrous, in many cases smaller spark plug gaps must be used as well as the use of a much hotter ignition system (see above). These higher cylinder pressures require more energy to jump the spark plug gap.
                              from http://www.centuryperformance.com/spark.asp

                              I dont think NGK is wrong about spark plugs and cylinder pressures, and I don't doubt my teachers as they've not steered me wrong before. believe what ya want, but Ive been in the automotive business since before I could drive em. there are few things I know better than the whys and hows of an internal combustion engine.

                              Im not trying to start a war, just doing my part to stop the misinformation.
                              OK

                              Comment

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