Can anybody clarify this carb modification?

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  • Guest

    #1

    Can anybody clarify this carb modification?

    Hi All...I saw this auction for a GREAT GS1000 that sold on eBay with a fantastic write up....eBay auction number 160612434898

    In his description he states the following:

    Carb overhaul: choke pick-ups drilled to .021?, pilots drilled to .018? to improve cold weather starting.. Bike starts instantly even at 40 degrees!

    Does this mean he drills out the carb bodies themselves for the choke pick-ups? Does he mean drilling out the pilot jets or the carb body there also? Has anyone ever done this before? Thanks
  • Big T
    Forum LongTimer
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    • Mar 2005
    • 12392
    • West Slope, OR

    #2
    He's drilling the pilot jets and the carb passage for the choke

    Easier to just buy a bigger pilot jet
    1978 GS 1000 (since new)
    1979 GS 1000 (The Fridge, superbike replica project)
    1978 GS 1000 (parts)
    1981 GS 850 (anyone want a project?)
    1981 GPZ 550 (backroad screamer)
    1970 450 Mk IIID (THUMP!)
    2007 DRz 400S
    1999 ATK 490ES
    1994 DR 350SES

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    • Nessism
      Forum LongTimer
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      • Mar 2006
      • 35790
      • Torrance, CA

      #3
      I've heard of people drilling jets because they were too cheap to purchase larger ones, but never heard of anyone drilling the pick up tubes. I recommend against it since the bike will run perfectly without doing this as long as the carbs are clean.
      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

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      • Guest

        #4
        This is what was confusing me...if you can go to bigger jets, which I have done once to adjust for pods, why not?

        But if you decide to drill the passages, does that really make a real difference? I'm still confused about..

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        • Nessism
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          • Mar 2006
          • 35790
          • Torrance, CA

          #5
          Just to clarify, yes, you can drill pilot jets to open them up and save money. Drilling the choke pick up tubes is necessary though since the hole is plenty large enough to supply fuel with it's present size.
          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

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          • TheCafeKid

            #6
            Originally posted by Nessism
            I've heard of people drilling jets because they were too cheap to purchase larger ones, but never heard of anyone drilling the pick up tubes. I recommend against it since the bike will run perfectly without doing this as long as the carbs are clean.
            ....and the valves are adjusted properly.

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            • hampshirehog
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              • Oct 2007
              • 12675
              • Hampshire. UK

              #7
              Drilling out jets used to be a not uncommon practice when workshops had a complete range of drill bits and had to wait a fortnight for new jets to turn up. If done properly it works fine. Now, as Big T suggests it's just easier to use new jets. And, repeat, it has to be done properly.

              Don't know why the choke tubes have been drilled - seems a bit pointless.

              Somebody will have to translate the numbers as well - I'm afraid I just can't be bothered to work with imperial measurements any more.
              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

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              • Agemax
                Forum Guru
                • Apr 2008
                • 8371
                • plymouth uk

                #8
                [QUOTE=hampshirehog;1451622]Drilling out jets used to be a not uncommon practice when workshops had a complete range of drill bits and had to wait a fortnight for new jets to turn up. If done properly it works fine. Now, as Big T suggests it's just easier to use new jets. And, repeat, it has to be done properly.

                Don't know why the choke tubes have been drilled - seems a bit pointless.

                Somebody will have to translate the numbers as well - I'm afraid I just can't be bothered to work with imperial measurements any more.[/QUOTE]
                lol, im with you there mate, im a metric man. cant be doing with all this imperial rubbishness
                1978 GS1085.

                Just remember, an opinion without 3.14 is just an onion!

                Comment

                • TheCafeKid

                  #9
                  [QUOTE=Agemax;1451626]
                  Originally posted by hampshirehog
                  Drilling out jets used to be a not uncommon practice when workshops had a complete range of drill bits and had to wait a fortnight for new jets to turn up. If done properly it works fine. Now, as Big T suggests it's just easier to use new jets. And, repeat, it has to be done properly.

                  Don't know why the choke tubes have been drilled - seems a bit pointless.

                  Somebody will have to translate the numbers as well - I'm afraid I just can't be bothered to work with imperial measurements any more.[/QUOTE]
                  lol, im with you there mate, im a metric man. cant be doing with all this imperial rubbishness
                  Me either and I'm a freaking "seppo"! I called a metal supply place a few weeks ago and asked about some Alu stock. Gave em my measurements, in mm cause that's what we were working with and they said they needed it in inches. I had to sit down and work it out and call back. Sheesh people. Get with the program. The entire world uses the metric system except us. I remember being taught in grade school, cause the whole world was gonna switch over and we needed to learn it. Never happened here. Should have. Makes a whole lotta much more sense. Especially when working on something that was designed and built around it like a Jap bike.

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                  • Greg B
                    Forum Mentor
                    Past Site Supporter
                    • Sep 2005
                    • 894
                    • Irvine, CA

                    #10
                    I don't do metric. (except for some threads) And I make my living measuring stuff.
                    The Three Horsemen
                    '85 GS1150ES (Current Income Eater)
                    '83 GS1100ES
                    ?77 XLCR

                    "Never ride faster than you can see. Besides, it's all in the reflexes."
                    Porkchop Express

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                    • Nessism
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                      • Mar 2006
                      • 35790
                      • Torrance, CA

                      #11
                      Yea, most of US industry is still on English/imperial unit of measure. I can go both ways but stay with English units when it comes to things like drill bits.
                      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

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                      • allojohn
                        Forum Sage
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                        • Jan 2011
                        • 3515
                        • NoMo, MN

                        #12
                        Been there and back again and again. Growing up in England I learned imperial measurement, then we went into Europe and switched to metric. Years later I emigrated to the US - went back to imperial. I'm in the surveying industry and much of our work is road design. In the '90's the Federal government mandated the use of metric measurement - back to metric. In the late 90's they let the metric mandate expire.! Back to imperial again!!!! Aaaarrgghh!.......and they will go metric again .......eventually.
                        -Mal

                        "The only reason for time is so that everything doesn't happen at once." - B. Banzai
                        ___________

                        78 GS750E

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                        • Agemax
                          Forum Guru
                          • Apr 2008
                          • 8371
                          • plymouth uk

                          #13
                          Originally posted by Nessism
                          Yea, most of US industry is still on English/imperial unit of measure. I can go both ways but stay with English units when it comes to things like drill bits.
                          we dont really need to know about that haha
                          1978 GS1085.

                          Just remember, an opinion without 3.14 is just an onion!

                          Comment

                          • Guest

                            #14
                            Thanks for the replies...so I'm gathering that we should just leave the choke tubes alone and go to bigger pilot jets if the need arises.

                            I love all the info on this forum and I'm always looking for new improvements/updates but this carb update intrigued me and I wanted other opinions. Thanks everyone.

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                            • rustybronco
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                              • Jul 2005
                              • 14961
                              • Marysville, Michigan

                              #15
                              Originally posted by Nessism
                              but stay with English units when it comes to things like drill bits.
                              Do you mean the 'English units' used in the number and letter series drills? (j/K Ed!)

                              "Hey Joe, ya have a spare # L drill?"
                              De-stinking Penelope http://thegsresources.com/_forum/sho...d.php?t=179245

                              http://www.thegsresources.com/_forum...35#post1625535

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