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  • #1

    Carb jets

    It's that time of year again, maintenance on the bike.
    I'm rebuilding my carbs because they've been sitting for 2 years with the same gas in them and of course this year it wont hardly run. Prior to this sitting spell the only issue I had was I heard valve ticking noise and a flat spot under 3k. I'm replacing the pilot jets and I was wondering if these sizes sounded right: 42.5 pilots, 132.5 mains. My only mod is a Kerker exhaust, and I'm considering a new K+N style air filter.
    I can usually do a basic R+R of the carbs (about half the time anyways), but I can't do any real tuning or picking jet sizes.
    any thought?

    Oh, and if you can point me to a good place to buy pilot jets that would be super
    Last edited by copracr; 04-02-2012, 03:40 PM.
    1980 XS1100SG Special
    Tags: None
  • #2
    Just drive it all year and you won't have any issues

    If you have the '80-'81 style carbs then those main jets are way to big. Start more in the 120 range.
    Last edited by natemoen; 04-02-2012, 03:41 PM.
    Nathan
    KD9ARL

    μολὼν λαβέ

    1978 XS1100E
    K&N Filter
    #45 pilot Jet, #137.5 Main Jet
    OEM Exhaust
    ATK Fork Brace
    LED Dash lights
    Ammeter, Oil Pressure, Oil Temp, and Volt Meters
    Green Monster Coils
    SS Brake Lines
    Vision 550 Auto Tensioner

    In any moment of decision the best thing you can do is the right thing, the next best thing is the wrong thing, and the worst thing you can do is nothing.

    Theodore Roosevelt

    Comment

    • #3
      Originally posted by natemoen View Post
      Just drive it all year and you won't have any issues

      If you have the '80-'81 style carbs then those main jets are way to big. Start more in the 120 range.
      Whoa, really? It ran like a well oiled machine from mid to high range, that seems like a big step
      1980 XS1100SG Special

      Comment

      • #4
        FWIW, my SG has a stock airbox and 4 into one exhaust. If it matters, there's a K&N filter in the box. It is jetted 110, 120, 120, 110, with 42.5 pilots. It runs great!
        Marty (in Mississippi)
        XS1100SG
        XS650SK
        XS650SH
        XS650G
        XS6502F
        XS650E

        Comment

        • #5
          Originally posted by natemoen View Post
          If you have the '80-'81 style carbs then those main jets are way to big. Start more in the 120 range.
          Is there an obvious way to tell if I have 80-81 style? And if I dont have that style is my jetting more appropriate? Like I said, I'm not real up on carbs but that seems like a big jump to run well.
          1980 XS1100SG Special

          Comment

          • #6
            Originally posted by copracr View Post
            Is there an obvious way to tell if I have 80-81 style?
            Look here..... http://www.xs11.com/forum/showthread.php?t=35964
            Fast, Cheap, Reliable... Pick any two

            '78E original owner - resto project
            '78E ???? owner - Modder project FJ forks, 4-piston calipers F/R, 160/80-16 rear tire
            '82 XJ rebuild project
            '80SG restified, red SOLD
            '79F parts...
            '81H more parts...

            Other current bikes:
            '93 XL1200 Anniversary Sportster 85RWHP
            '86 XL883/1200 Chopper
            '82 XL1000 w/1450cc Buell, Baker 6-speed, in-progress project
            Cage: '13 Mustang GT/CS with a few 'custom' touches
            Yep, can't leave nuthin' alone...

            Comment

            • #7
              The quickest & easiest way to tell 80-81 from earlier carbs is by the support brackets.
              78-79 only have the one L bracket joining all 4 carbs & carbs are all joined at top by small hourglass shaped brackets attached to top covers.

              80-81 have the L bracket on the bottom plus a one piece strap joining the carbs at top just above intake openings. No small brackets joining carbs at top covers.
              Tom Clisham

              Age is relative YOU WON"T GET OLD TIL YOU SELL THE BIKE
              _____________________________________________

              '78xs1100E ,all stock & original GONE TO WISCONSIN

              '80 SG Vetter fairing,hard bags,trunk,fork brace,
              stock headers with fishtail mufflers,black & beautiful GONE TO ARIZONA

              79SF lowered,jardine 4/2 exhaust,pod filters,drilled rotors,fork brace, bar hopper

              79SF 1 owner,8000 miles, restoring to completely original ( I hope) GONE TO FRANCE

              Comment

              • #8
                80-81 Specials run 110's across all four carbs stock. The Standard, Yamaha did the one step bigger for middle two cyl. with 115's/120's. They dropped that as it was a bit anal even tho inner two cyl. run a bit hotter. Difference between the two models was the metering rods, which accounts for the jetting differences. The XJ stock jetting was 112.5 all across. With your exhaust mod I'd go with 112.5's across all four. 42.5 IS also the stock pilot jetting....leave it that way. Use Genuine Mikuni main jets/pilot jets or you WILL have a tuning nightmare.
                81H Venturer1100 "The Bentley" (on steroids) 97 Yamaha YZ250(age reducer) 92 Honda ST1100 "Twisty"(touring rocket) Age is relative to the number of seconds counted 'airing' out an 85ft. table-top.

                Comment

                • #9
                  Steves link will help you tell which you have. Even if you do have the early carbs, then your jetting is too lean.
                  Nathan
                  KD9ARL

                  μολὼν λαβέ

                  1978 XS1100E
                  K&N Filter
                  #45 pilot Jet, #137.5 Main Jet
                  OEM Exhaust
                  ATK Fork Brace
                  LED Dash lights
                  Ammeter, Oil Pressure, Oil Temp, and Volt Meters
                  Green Monster Coils
                  SS Brake Lines
                  Vision 550 Auto Tensioner

                  In any moment of decision the best thing you can do is the right thing, the next best thing is the wrong thing, and the worst thing you can do is nothing.

                  Theodore Roosevelt

                  Comment

                  • #10
                    Also, on the later models the idle adjustment knob is on the bottom torards the front, the earlier models have it on the top towards the rear.
                    Skids (Sid Hansen)

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

                    Comment

                    • #11
                      yep, they look like originals. Guess I should start working on this
                      1980 XS1100SG Special

                      Comment

                      • #12
                        Originally posted by natemoen View Post
                        Steves link will help you tell which you have. Even if you do have the early carbs, then your jetting is too lean.
                        Wait, smaller number=smaller hole right?? I'm running a way too big main jet with 132.5's in there. I should start with a 120 maybe?

                        I got Mikuni pilots: http://www.amazon.com/gp/product/B0050AO4Z2

                        They're 42.5's

                        I also ordered a K+N while I was there.
                        1980 XS1100SG Special

                        Comment

                        • #13
                          '80+ carbs had 110-120 main jets stock. '78-'79 had 137.5 stock. Becayse of the design differences you need to stay in that range. So if you are sure you have the later carbs then I would probably start at 115 and tune from there, may need to go higher but you won't know till you run it some.
                          Nathan
                          KD9ARL

                          μολὼν λαβέ

                          1978 XS1100E
                          K&N Filter
                          #45 pilot Jet, #137.5 Main Jet
                          OEM Exhaust
                          ATK Fork Brace
                          LED Dash lights
                          Ammeter, Oil Pressure, Oil Temp, and Volt Meters
                          Green Monster Coils
                          SS Brake Lines
                          Vision 550 Auto Tensioner

                          In any moment of decision the best thing you can do is the right thing, the next best thing is the wrong thing, and the worst thing you can do is nothing.

                          Theodore Roosevelt

                          Comment

                          • #14
                            I would start with the 120s.
                            Life is what happens while your planning everything else!

                            When your work speaks for itself, don't interrupt.

                            81 XS1100 Special - Humpty Dumpty
                            80 XS1100 Special - Project Resurrection


                            Previously owned
                            93 GSX600F
                            80 XS1100 Special - Ruby
                            81 XS1100 Special
                            81 CB750 C
                            80 CB750 C
                            78 XS750

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                            • #15
                              Im running 120 main 45 pilots with pods and kerker 4to1. Plugs look good. Its needs some more fine tuning. Now my clutch is unhappy.
                              95 Dodge 2500 RCLB 2wd 5spd cummins 303k miles. Alot of go fast parts and smoke.

                              80 xs1100sg 16k miles. Kerker 4 to1 Pods with stock airbox tubes. 120 mains 45 pilots slipping clutch

                              86 Samurai soft top 16v tracker motor, 6.5 to 1 t-case gears 34" tractor tires among other stuff

                              Horsepower is how fast you hit the wall, Torque is how far you take the wall with you.

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