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'82 GS 650 glz - Carburation issue (probly)

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    #46
    Finally, bike's happy, I'm happy

    Well, after much tinker, research, and more tinker, the bike's now running very well. Starts, idles, revs and pulls smoothly all the way to redline. No stumble, or flat spots, great roll on response at all levels.
    Wow. This thing's a ball to ride.
    Thanks for all the information, and more importantly for the encouragement to keep working on it.

    First of all, my initial issues were mainly caused by crappy original intake tubes, which were brittle & cracked. I blamed the 6-Sigma jet kit. The intake tubes & o-rings were replaced and it really got me somewhere, but still lots of issues, and the indications seemed that it was running too rich . I went down in jet sizes from the 6-Sigma kit, and generally it got worse; & since it loved the choke when it balked, I then started working my way back up in jet sizes, finding improvement each time. I lost track of how many times I had the carbs off, and how many sets of jets I got, but I think I tried at least 4 or 5 different combinations. Along the way was lots of learning (I can pull the carbs off in 20 minutes now, change jets and re-install them in less than an hour total) and some sloppy or careless work on my behalf. Never underestimate the value of attention to detail at every step.
    One issue I had, I blamed on carbs and it was the plugs. Now there's one step hotter plugs, and new NGK plug caps, which made a surprising difference.
    The starving issue noted on my last post was, well ... low on gas. Duh. I made the mistake of trusting the very vague gas gauge, which showed a 1/4 tank & I'd just put a gallon in it. (I had never ridden this thing before I started working on it - it's my daughter's bike, she picked it up in neglected condition. I had originally started it on the stand, then commenced all this work, not really knowing what sort of baseline I was dealing with). So, dumbassness at play. "Genius has its limits, but ignorance knows no bounds".

    Anyway, for the sake of conclusion, and for the "pods and exhaust" topic, here's the final score:
    (SitStat: '82 gs650 gl, 17K miles, 140psi +/-compression; K & N dual pods, drilled out stock exhaust; & sea level riding for the most part)
    Pilot jets are up one size (45). Mixture screw 2.5 turns out. Floats set, & rechecked (first time they were off, and it was just sloppy work on my end - a digital mike makes all the difference).
    The needle now has no spacer above the clip, & a small nylon spacer + one thin steel washer (from 6-Sigma) below the clip. Vacuum slide hole drilled out w/ #40 drill bit. Vacuum slide springs clipped about 3/16ths inch. Main jets are Mikuni's (I doubted the quality of the AB jets supplied in the kit) 127.5 on the outer cylinders, and 130's on the center pair. I also closed/covered about 1/3 of the surface of the K & N dual pods.

    Some of these things are a bit contrary to the advice I'd received, but I just kept trying different things following trial and error until it started showing improvement. All bikes are different, and riding conditions vary of course, too.

    I kinda hate to turn this thing back over to my daughter now that it's done, it's so much fun to ride.

    Comment


      #47
      OK, looks good! So if I understand you covered a part of the k&n pods to be able to ride it well with 130 /127.5.. mini ones.. why do not you try to remove the covering tape and put bigger jets?
      Nevertheless the size of the jets you use is geTring closer than my settings (and those of tkent02). I have velocity stacks, open exhaust, and have increased the air flow in the head by milling it. I still have to try but I put 152.5 mains...I think i will be close enough to ride it

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        #48
        Could you say more about the size of the holes that you drilled for the vaccum parts?

        Comment


          #49
          Originally posted by boris.h View Post
          Could you say more about the size of the holes that you drilled for the vaccum parts?
          He said he used a #40 drill bit. Besides using measurements in inches or millimeters, drill bits are also sized by numbers. Click HERE to see the conversion from one system to another, you will have a better idea of just how big that is.

          .
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          Comment


            #50
            "why do not you try to remove the covering tape and put bigger jets?"
            Well, first of all, because tape is free (almost) & on hand, and jets are $25/set + shipping, (I have lots invested in the trial/error plan thus far) and second of all- it runs as good as I ever hoped it would, and third: I'm a bit tired of messing w/ it, and lastly, I wanted to cover the tops anyway to keep water out of the air cleaners in the event the bike was ever left outside in the rain (a distinct Oregon possibility). Using black tape it doesn't look cheesy either.
            I also wonder if it affects the vacuum a bit... in a helpful way. Going from one size smaller jets to this arrangement was a remarkable improvement.
            But, if absolute performance was the goal, with no worries about rain, more patience, and another set of jets, I'd certainly give that a try. I just decided to quit while I was ahead.

            Comment


              #51
              Originally posted by boris.h View Post
              Could you say more about the size of the holes that you drilled for the vaccum parts?
              FYI- The bit came with the kit from 6-Sigma. I think DynoJet kits include a drill as well, not certain about the size. #40=0.098 in; 2.489mm.
              IMG_3023.jpg
              Last edited by Guest; 07-02-2016, 02:01 PM.

              Comment


                #52
                OK thanks a lot for your answers. You also confirmed me that #40 is literally a size in inches so yes I can easily convert it into mm.
                Could you explain what is the goal in drilling the vaccum holes and cutting the springs? Get richer in low rpm?

                Comment


                  #53
                  This is from the instructions that came with the jet kit:
                  "The stock bike has lazy throttle response due to heavy slide springs that regulate the vacuum pistons (carburetor slides).
                  * By clipping the springs to the desired tension, the throttle response will become instantaneous and the delay on full throttle shifts will be eliminated. The result is a much more responsive engine.
                  * By enlarging or adding the slide's air displacement holes, you will be allowing them to lift and return quickly, to match the new spring tension, and provide the desired improved response."
                  "Start with one full loop (1/8th inch)"....{this pertains to clipping the springs, not drilling the hole, BTW.}

                  FYI- I got another set of springs off eBay for cheap (as a back-up/spare set) in case things went against the objective. The slides can be found as well... but even used ones aren't cheap. I took a chance, and worried I'd made a mistake until I got it running well.

                  I'm pretty sure the DynoJet kit also includes a drill for the slides. A difference seems to be that DynoJet includes a fitting for the air orifice on the right side of the carb that is evidently glued into place, reducing the size of the orifice. Nothing in the kit I used mentioned this at all. Perhaps there are member's who've used the DynoJet kit that can chime in here about that

                  I continue to be please with the performance of the bike in its current state of tune.
                  Last edited by Guest; 07-03-2016, 08:24 PM. Reason: spelling error & clarification

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