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GS450 idles at 3-4.5k

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    GS450 idles at 3-4.5k

    Hey folks.
    Been wrestling with this bike for a few months. Worked off a lot of PO issues to finally get it running enough to get it on the road legally. Legality does not equate to ride-able though. I took the carbs off and somewhat cleaned them. I say somewhat because I haven't replaced the O-rings YET. They're ordered and en route.

    I received the bike with what looked like air filters from a weed wacker just kinda shoved onto the intake. They didn't even match. There's an aftermarket exhaust also. I picked up a set of UNI pod filters. Before you comment, there's also an exhaust on it, so I was going to have to deal with too much air anyhow. I'm not going for original spec, so don't bother trying to convince me of that route. Even if I did get everything back stock, it'd be the same procedures in an attempt to make it all run right again anyhow since the PO had no regard for factory anything. That sort of advice isn't helping. It's trying to turn my motorcycle into a revival for the factory specs. I don't want factory. I want working with what resources I have. If I wanted to spend another $800 to get all OEM stuff on this bike, I would have just bought a different bike. But I didn't. I bought this one.

    Now that I've addressed the purists who claim that no cv carb can be tuned without an airbox and other such negativity, lets get to my issue. I turn the bike on, and it instantly shoots to around 4000 RPM. With the increased air both in and out, I believe the issue is now too much fuel. I can take the throttle cable completely off and it still does this, so no adjusting that will help. Pilot and other such adjustments are too small to really make a difference. There is suggestions that there's an air leak, which I may have considered if I didn't just have a ton of air already being supplied with little restriction already. An air leak may be the issue, but i'd like to work from the fuel side first. The main jets have "115" on them. My thoughts, based on what I've read, watched, and gleened from other forum posts on here is that I need a more restrictive main jet. If that is a wrong idea, please do correct me.

    I have actually ridden this bike with the idle issue, which made it quite fun when it came time to shift. So, the engine and tranny work great. I just have to calm this hellcat down a bit. Thanks in advance for advice I can act upon.

    If you want photos or video of something, let me know.

    #2
    You need a less restrictive main jet...115 is stock...you've got more air flow, you need more fuel.
    1982 Suzuki GS450TZ
    1982 Suzuki GS1100EZ

    Comment


      #3
      What he said.
      https://drive.google.com/open?id=0B9zH8w8Civs8ejBJWjdvYi1LNTg&resourcekey=0-hlJp0Yc4K_VN9g7Jyy4KQg&authuser=fussbucket_1%40msn.com&usp=drive_fs
      1983 GS750ED-Horsetraded for the Ironhead
      1981 HD XLH

      Drew's 850 L Restoration

      Drew's 83 750E Project

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        #4
        Thanks guys. Think just upping to 120 will be enough?

        Comment


          #5
          Originally posted by Gambit View Post
          Thanks guys. Think just upping to 120 will be enough?
          First, if the throttles are completely closing there is no way that the idle circuit will supply enough to get 4K rpm, and the main jet and slide circuit is incapable of getting enough fuel past the throttle butterflies to do it either, assuming the slides aren't stuck. So you've got a problem with the cable or some aspect of the throttle butterfly control mechanism that's hanging the thing up. Fiddling with the main jet will not do anything to address the problem.

          Main jet size affects wide open throttle at high rpm only. Have you completely backed off the idle speed adjuster? Have you looked to see that the butterflies are closing fully? Do you have some slack in the throttle cable? Do you have a manual?

          Hoe about the choke system? Is it shutting off completely? That, plus an air leak would give you about 400 rpm idle.
          '82 GS450T

          Comment


            #6
            You should learn how the carburetors work.
            http://img.photobucket.com/albums/v5...tatesMap-1.jpg

            Life is too short to ride an L.

            Comment


              #7
              Tkent, that's what I'm here for. Do you have any other insight other than "you don't know things." I know I don't know things. That's why I'm on this site. So if you don't want to take the time to type something out or at least provide a link, then I'm sure as hell not going to read anything. That's kind of how it works. So, move on. I don't need your negativity.

              Comment


                #8
                That was not intended for you, it was intended for the guys suggesting a main jet swap to fix a high idle. Have you tried adjusting the idle speed screw? If that doesn't work you probably have an air leak. It will need different jetting to make it run well with those UNI filters, but that's not what the high idle is about. One thing to look at, the choke lever on the 450 is opposite of the other GSes, down is full choke and will make the engine race. Maybe that's what you have?

                CVs can be tuned for anything you want.
                http://img.photobucket.com/albums/v5...tatesMap-1.jpg

                Life is too short to ride an L.

                Comment


                  #9
                  Ok, here's what I've got. I can completely disconnect the throttle cable entirely and it does this. The manual will point at things but not elaborate on what it does or carburetor theory. My slides are not sticking, and the floats, and float needles are clean and operating properly as far as i can test for (gravity feed some fuel and see if the needle stops it.) The choke is "closed" while it idles at 4k. If I "open" it, it reaches about 6k.

                  Comment


                    #10
                    OK, is the idle speed screw having any effect? It's the big knob between the carburetors. Screw it out and the idle should slow down.
                    http://img.photobucket.com/albums/v5...tatesMap-1.jpg

                    Life is too short to ride an L.

                    Comment


                      #11
                      I'm going to research about these butterflies. Do I need a net?

                      Comment


                        #12
                        Just the internet.
                        http://img.photobucket.com/albums/v5...tatesMap-1.jpg

                        Life is too short to ride an L.

                        Comment


                          #13
                          I've toyed with that and it hasn't done anything. No response. I didn't take it to the full extent in either direction, I just did a couple turns and figured whatever was wrong was bypassing that.

                          Comment


                            #14
                            If it helps any, while riding it, I can control engine speed with braking while in gear. I figure this is just the transmission slowing down the engine. But I'm providing all the information I can at this point. The PO was using the kill switch to throttle down to shift.

                            Comment


                              #15
                              Next choice, a big air leak? Around the boots to the head? Wiggle the carbs, does the idle fluctuate?
                              http://img.photobucket.com/albums/v5...tatesMap-1.jpg

                              Life is too short to ride an L.

                              Comment

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