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    Carburetors are driving me insane.

    Starts when cold just fine, take off the choke and she idles beautifully.

    Drive around town for a few minutes, come to a red light, the idle is bouncing all over the place. When it drops low, the bike back fires and then sometimes the RPM's shoot back up, sometimes it will die.

    I'm pulling my hair out!

    It has a Dynojet Stage 3 kit and the slides are drilled.

    One thing I noticed, and this made it a little better, was the tops of of Unifilters were coming off and making the bike run lean as hell. That made it a bit better when I glued those back on. I'm starting to wonder if maybe my Unifilters are just so old and crappy that they are causing it to run correctly. I'm ordering some APE pods soon, so that question will be answered.

    The carbs have been bench synced, but I have not adjusted the idle screws with the highest idle method because I can't Valves have yet to be adjusted as well. I was planning to do all of that next weekend.

    I haven't done a proper plug chop either, because I wanted to get the run ability issue taken care of first.


    Any thought at all about this? Maybe I need to go home and do a plug chop for the idle circuit. How do you even adjust the idle circuit??

    :EDIT:
    After doing some Googling, it seems that the pilot circuit is adjustable? All my pilot jet's are screwed all the way in...is that making it rich at idle?
    Last edited by Guest; 06-08-2011, 02:17 PM.

    #2
    If the filters are falling to bits it sounds as if it's time to replace them - and i wouldn't do anything else until you have. And then check those valve clearances!

    To adjust the idle circuit you screw the mixture screw in and out - highest rpm method is the easiest and simplest way.
    79 GS1000S
    79 GS1000S (another one)
    80 GSX750
    80 GS550
    80 CB650 cafe racer
    75 PC50 - the one with OHV and pedals...
    75 TS100 - being ridden (suicidally) by my father

    Comment


      #3
      Originally posted by hampshirehog View Post
      If the filters are falling to bits it sounds as if it's time to replace them - and i wouldn't do anything else until you have. And then check those valve clearances!

      To adjust the idle circuit you screw the mixture screw in and out - highest rpm method is the easiest and simplest way.
      Their not falling to bits though. Just the glue let the chrome tops come off...I used Gorilla Rubber Cement and put them back on. Other than that, they look fine.

      Comment


        #4
        Originally posted by Krunk_Kracker View Post
        Their not falling to bits though. Just the glue let the chrome tops come off...I used Gorilla Rubber Cement and put them back on. Other than that, they look fine.
        Theyre junk... replace em bro. And you cant possibly begin to adjust carb mixtures without adjusted valves. When you adjust the valves, thing will change slightly, you should probably do that first. Other than that, you're kinda shooting at these carbs all wrong bro.

        What bike??

        Comment


          #5
          Sorry you are getting frustrated but basic maintenance must be performed before you go to the fine tuning stage. Adjust the valves, vacuum sync the carbs, tweak the pilot screws. Judge your idle situation after this is complete.
          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


            #6
            Originally posted by TheCafeKid View Post
            Theyre junk... replace em bro. And you cant possibly begin to adjust carb mixtures without adjusted valves. When you adjust the valves, thing will change slightly, you should probably do that first. Other than that, you're kinda shooting at these carbs all wrong bro.

            What bike??
            Yeah, I wasn't expecting to get it to run like a sewing machine, but I figured I could get it running well enough. Guess I just need to buckle down and get the valves done. Replacing those Unifilters with some APE pods just as soon as a check clears...I don't wanna touch my savings, (I hate being tempted too, lol)

            It's my GS650GL

            Originally posted by Nessism View Post
            Sorry you are getting frustrated but basic maintenance must be performed before you go to the fine tuning stage. Adjust the valves, vacuum sync the carbs, tweak the pilot screws. Judge your idle situation after this is complete.
            OK, fair enough. I just thought that I could get a "good enough" tune going to hold me over until the valve job was done.



            Just for my knowledge though, the pilot jet's are adjustable?

            Comment


              #7
              Originally posted by Krunk_Kracker View Post
              Yeah, I wasn't expecting to get it to run like a sewing machine, but I figured I could get it running well enough. Guess I just need to buckle down and get the valves done. Replacing those Unifilters with some APE pods just as soon as a check clears...I don't wanna touch my savings, (I hate being tempted too, lol)

              It's my GS650GL



              OK, fair enough. I just thought that I could get a "good enough" tune going to hold me over until the valve job was done.



              Just for my knowledge though, the pilot jet's are adjustable?
              THe jets themselves are NOT adjustable...They need to be screwed all the way in to their homes.. And the rubber plugs must be installed over them as the pilot jet is fed through the main jet on the CV carbs.

              what IS adjustable is the mixture screws. These need to be set, for a start, at around 2.5 turns out. Your float levels are also VERY VERY important. If they're set to high (as in the bowls get too much fuel before the floats shut the float valve....think of it like the tank on your toilet if you're not following...when the water reaches a certain level, the big rubber float thingy shuts off the flow of water) the bike will get too much gas at idle especially, and cough and fart and drown and the lot...

              BUT, you really do need to adjust the valves...If you're still having issues afterward, then look to the carbs. but you need a known good baseline to start from, and that starts with properly adjusted valves...

              Comment


                #8
                How does it do after a little time has passed?
                First thing I though. Fuel tank vents..

                Every single valve on my 850 were under specs but "movable". The bike ran and started just fine. After adjustment I could not tell a single bit of difference except that they seemed a little more noisy. Perhaps it's just me.
                Thats not to say you dont need to do it. By all means it must be done. Just saying I could not tell they were tight by running the bike.
                I'm not sure if the sync was different cause I never sync'd em till afterwards.
                Put new plugs in it.
                sigpic

                82 GS850
                78 GS1000
                04 HD Fatboy

                ...............................____
                .................________-|___\____
                ..;.;;.:;:;.,;.|__(O)___|____/_(O)|

                Comment


                  #9
                  Originally posted by TheCafeKid View Post
                  THe jets themselves are NOT adjustable...They need to be screwed all the way in to their homes.. And the rubber plugs must be installed over them as the pilot jet is fed through the main jet on the CV carbs.

                  what IS adjustable is the mixture screws. These need to be set, for a start, at around 2.5 turns out. Your float levels are also VERY VERY important. If they're set to high (as in the bowls get too much fuel before the floats shut the float valve....think of it like the tank on your toilet if you're not following...when the water reaches a certain level, the big rubber float thingy shuts off the flow of water) the bike will get too much gas at idle especially, and cough and fart and drown and the lot...

                  BUT, you really do need to adjust the valves...If you're still having issues afterward, then look to the carbs. but you need a known good baseline to start from, and that starts with properly adjusted valves...
                  Float level was just done, two weekends ago, but double checking never hurts anything! I'll double check. I bought new plugs for the pilot jets as well.

                  I'm going to have to start a new thread about adjusting the valves, I get how to do it, but I need to know what all to buy, tool wise.

                  Originally posted by Octain View Post
                  How does it do after a little time has passed?
                  First thing I though. Fuel tank vents..

                  Every single valve on my 850 were under specs but "movable". The bike ran and started just fine. After adjustment I could not tell a single bit of difference except that they seemed a little more noisy. Perhaps it's just me.
                  Thats not to say you dont need to do it. By all means it must be done. Just saying I could not tell they were tight by running the bike.
                  I'm not sure if the sync was different cause I never sync'd em till afterwards.
                  Put new plugs in it.
                  Has new plugs, but I also have two more new sets, haha.

                  The bike has JUST gotten back on the road. I replaced the entire ignition with all NGK and Dynatek parts. Carb's were all dipped for 24 hours, oring'ed and Dynojet stage 3 installed.

                  After time has passed, it idles like a race bike would...very sporadic.

                  Guess I'm just gonna have to bite the bullet and get it done quick.


                  I just called the local Suzuki place and they have a master shim set that they part out, so that's good. The bad thing is the bastards are $7 a piece.

                  Comment


                    #10
                    Originally posted by Krunk_Kracker View Post
                    I'm going to have to start a new thread about adjusting the valves, I get how to do it, but I need to know what all to buy, tool wise.
                    I just called the local Suzuki place and they have a master shim set that they part out, so that's good. The bad thing is the bastards are $7 a piece.
                    Do a search on here for valve adjustments as this question has been asked a lot. I got the valve adjustment tool from Z1 for not a lot of money as well as a set of metric feeler gauges. Past that you'll need a new valve cover gasket and a set of regular old tweezers.

                    Make sure you ALWAY have a shim in each cylinder when checking them - NEVER rotate the engine without one. You can also do a search for the Shim club on here and get them for a lot less money.
                    Cowboy Up or Quit. - Run Free Lou and Rest in Peace

                    1981 GS550T - My First
                    1981 GS550L - My Eldest Daughter's - Now Sold
                    2007 GSF1250SA Bandit - My touring bike

                    Sit tall in the saddle Hold your head up high
                    Keep your eyes fixed where the trail meets the sky and live like you ain't afraid to die
                    and don't be scared, just enjoy your ride - Chris Ledoux, "The Ride"

                    Comment


                      #11
                      My bike was shaking like a hurricane, kept stalling, Idle was nuts....you name it.

                      I Finally did the valves......problems Gone!

                      Bike was as smooth as a clock.
                      ------

                      Even in your average used car....you'd be surprised how much power you can restore, just by adjusting the valves/rockers.

                      Comment


                        #12
                        Originally posted by cowboyup3371 View Post
                        Do a search on here for valve adjustments as this question has been asked a lot. I got the valve adjustment tool from Z1 for not a lot of money as well as a set of metric feeler gauges. Past that you'll need a new valve cover gasket and a set of regular old tweezers.

                        Make sure you ALWAY have a shim in each cylinder when checking them - NEVER rotate the engine without one. You can also do a search for the Shim club on here and get them for a lot less money.

                        Z1 Enterprises specializes in quality Motorcycle parts for Honda, Kawasaki, Suzuki and Yamaha Classic Japanese motorcycles from the 1970's and 1980's.


                        That one there?

                        Maybe I'll go with the zip tie method, it's a lot cheaper, haha.

                        Comment


                          #13
                          Originally posted by Krunk_Kracker View Post

                          Maybe I'll go with the zip tie method, it's a lot cheaper, haha.
                          A lot easier too.
                          sigpic

                          82 GS850
                          78 GS1000
                          04 HD Fatboy

                          ...............................____
                          .................________-|___\____
                          ..;.;;.:;:;.,;.|__(O)___|____/_(O)|

                          Comment


                            #14
                            Hi,

                            Originally posted by Krunk_Kracker View Post
                            I'm going to have to start a new thread about adjusting the valves, I get how to do it, but I need to know what all to buy, tool wise.
                            The only task-specific tool you need is the tappet tool. A pair of heavy tweezers or hemostats can come in handy for grabbing the shims. Don't forget a new valve cover gasket. Otherwise you just need regular tools to remove the valve cover and a good feeler gauge to measure the clearances. Most of your questions should be answered in this PDF file:

                            Valve Adjustments (8 Valve)

                            If you don't want to buy the $15 tappet tool you can use the "zip tie" method.

                            Zip Tie Supplement (by Mr. Matchless)

                            I prefer using the tappet tool but many like sticking zip ties in their cylinders to hold the valves open.

                            Z1 has the best prices on shims at just over $5 each, the last time I checked.



                            Thank you for your indulgence,

                            BassCliff

                            Comment


                              #15
                              You want to be careful with the zip tie method. I've used it, still use it from time to time if the tapper tool is fighting me, which it sometimes does for whatever reason on the inside cylinders of some models. But you need to make sure your zip tie is doubled over, and is a nice pliable new tie and not hard and brittle. I made that mistake once. ONCE. It resulted in pulling the head after the tie broke and half of it fell into the cylinder.... Sucked. A simple valve adjustment turned into a top end rebuild pretty quick...

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