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  • carb jetting

    ok after read the rejetting tips here is the question i have a 80 sg with stock exhaust and soon to be individual air filters now reading the rejetting i come up with 112.5 and 122.5 but i cant find those sizes but i can get 115 and 125 's will this work right and should i got up on on the pilot jet but seeing how i didnt got up 3 jet sizes i should not need to ?
    80 xs11 sg

  • #2
    Give'em a try

    Jets should be sized in 2.5 increments so your mains will be one size larger than the recommendation. The recommendations are not set in stone but are a starting point. Since the mains do not really come into play until after half throttle, give them a try. Your pilots handle from off idle through about 1/3 throttle and some of this can be adjusted with the idle mix screws.

    My 79 special has individual air filters and 4 into 1 header. I am up four sizes on the mains and one on the pilot jet....not exactly what the tuning recommendations say but that seems to be the sweet spot for my bike. So, I would change the jets, go for a little ride and see how it feels. Then read the spark plugs and see if they are light tan.
    Mike Giroir
    79 XS-1100 Special

    Once you un-can a can of worms, the only way to re-can them is with a bigger can.

    Comment


    • #3
      I'm just not understanding why you can't find those sizes?? They should be available. I don't know where you looked, but they are out there. Good luck with whatever you decide. A tad on the rich side would be better than lean anyway with these bikes.

      Where are you getting the Pod filters from?? You might do a search and read about them... quite a bit of discussion about suppliers and problems with some.

      Tod
      Try your hardest to be the kind of person your dog thinks you are.

      You can live to be 100, as long as you give up everything that would make you want to live to be 100!

      Current bikes:
      '06 Suzuki DR650
      *'82 XJ1100 with the 1179 kit. "Mad Maxim"
      '82 XJ1100 Completely stock fixer-upper
      '82 XJ1100 Bagger fixer-upper
      '82 XJ1100 Motor/frame and lots of boxes of parts
      '82 XJ1100 Parts bike
      '81 XS1100 Special
      '81 YZ250
      '80 XS850 Special
      '80 XR100
      *Crashed/Totalled, still own

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      • #4
        I found the same issue while looking for jets for my 80G. It seems that from 110 to about 125 the sizes go up in increments of 5 and then from there on they go up by 2.5. Check Mikes xs, they have the whole lineup and good prices.
        If it aint broke....it aint mine!:(
        80G The Big unit
        72 BSA Rocket Three "Main Squeeze"
        84 GS1150ES "Big Sue"
        79 Special (Tomcat's) as yet unnamed

        Comment


        • #5
          Hey TJ,

          Have you pulled the mains out yet?? Contrary to what the "Book" says, many of us have found the same size jets across all 4 cylinders, instead of the staggered setup that is published!?

          So it's not really necessary to stagger them, was just Yamaha's attempt at trying to keep the inner cylinders cooler by making them a little richer! You may not need to try to find so many different sizes.

          Bike Bandit has them, but can be a little hard to find them on their site. You have to go and select carb accessories, and then you'll find them.
          T.C.
          T. C. Gresham
          81SH "Godzilla" . . .1179cc super-rat.
          79SF "The Teacher" . . .basket case!
          History shows again and again,
          How nature points out the folly of men!

          Comment


          • #6
            jets

            there are two differnet jets bike bandit has them but the have the small round head not the large round but the treads are the same can i use either i know that the carb has the large as oem but i dont think that matter does it ?
            80 xs11 sg

            Comment


            • #7
              Hey TJ,

              Well, I'll be damned but the large head BS30/96 style main jets are NO LONGER shown!? I don't know what to say, Xcept I'm sorry! But, no, you can't use the smaller head ones, those are used for air jets, but you need the large head style for the carbs!

              BikeBandit's LIVE HELP was closed, don't know if it's a matter of accidental omission, or if they have truly quite carrying them, but I would think they would want to carry the large head jets!?!?
              Again, sorry for the mis-information!
              T.C.
              T. C. Gresham
              81SH "Godzilla" . . .1179cc super-rat.
              79SF "The Teacher" . . .basket case!
              History shows again and again,
              How nature points out the folly of men!

              Comment


              • #8
                If you write Bike Bandit they will order them for you. Tell them what you are looking for and what size.
                79 F full cruiser, stainless brake lines, spade fuses, Accel coils, modded air box w/larger velocity stacks, 750 FD.
                79 SF parts bike.

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                • #9
                  Have you checked the prices for the N100.604 main jets from Bike Bandit??? $10.68/ea

                  I ordered 4 N100.604 Mikuni jets from JetsRUs for $12.36 plus $7.23 shipping & handling and received them within 5 business days via USPS. Not as cheap as some but definitely cheaper and faster than Bike Bandit.

                  Comment


                  • #10
                    Re: jets

                    If they are "main jets" it does not matter if they are the smaller diameter of the big diameter. They are metered the same. I think the hex style is different though (not sure).

                    Originally posted by tjfisher30
                    there are two differnet jets bike bandit has them but the have the small round head not the large round but the treads are the same can i use either i know that the carb has the large as oem but i dont think that matter does it ?
                    Skids (Sid Hansen)

                    Down to one 1978 E. Stock air box with K&N filter, 81H pipes and carbs, 8500 feet elevation.

                    Comment


                    • #11
                      Originally posted by Brian_D
                      Have you checked the prices for the N100.604 main jets from Bike Bandit??? $10.68/ea

                      I ordered 4 N100.604 Mikuni jets from JetsRUs for $12.36 plus $7.23 shipping & handling and received them within 5 business days via USPS. Not as cheap as some but definitely cheaper and faster than Bike Bandit.
                      faster maybe not sure yet but cheaper no i just got 8 jets 2 sets 112.5s and 115 for 17.27 and 4.00 for total of 21.98
                      80 xs11 sg

                      Comment


                      • #12
                        Re: Re: jets

                        Originally posted by skids
                        If they are "main jets" it does not matter if they are the smaller diameter of the big diameter. They are metered the same. I think the hex style is different though (not sure).

                        skids your right well at least that what the guys at motorcyclecarbs said they will fit and both large heads and small heads the holes are the same and the threads and depth the only diffrence is the large head is 8mm and small is 6mm but i will let you all know for sure when they come in i will be trying them if somehow they dont work whats 20 buck ive screwed up worse before for a lot more money
                        80 xs11 sg

                        Comment


                        • #13
                          thats a good price - Bandit charged me $10.68 plus shipping for qty 1 jet (#110) - and it took almost 20 days for delivery.

                          Comment


                          • #14
                            Mike's xs has the large round head jets you need. They are 2 for $6.00 The hex head jets will not work. They have different threads.
                            If it aint broke....it aint mine!:(
                            80G The Big unit
                            72 BSA Rocket Three "Main Squeeze"
                            84 GS1150ES "Big Sue"
                            79 Special (Tomcat's) as yet unnamed

                            Comment

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