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How many "steps" between 80 and 102?

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    How many "steps" between 80 and 102?

    I'm rejetting my bike for the new pipes, and I've been told to go 2-3 on the mains. Since my pilot fuel screws were broken, I ordered some GS750 carb kits that included the screws needed and they came with mains marked "102." The mains in the 550 kits are marked 80. How many steps are between the two? According to Jets R Us, it looks like a 9 step difference!

    #2
    The jets come in 2.5 increments.
    80-82.5-85 ect.....
    1983 GS 1100E w/ 1230 kit, .340 lift Web Cams, Ape heavy duty valve springs, 83 1100 head with 1.5mm oversized SS intake valves, 1150 crank, Vance and Hines 1150 SuperHub, Star Racing high volume oil pump gears, 36mm carebs Dynojet stage 3 jet kit, Posplayr's SSPB, Progressive rear shocks and fork springs, Dyna 2000, Dynatek green coils and Vance & Hines 4-1 exhaust.
    1985 GS1150ES stock with 85 Red E bodywork.

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      #3
      Originally posted by chef1366 View Post
      The jets come in 2.5 increments.
      80-82.5-85 ect.....
      I've heard that, as well as "they come in 5s, 2.5 is a half-step"

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        #4
        Originally posted by Pendulum View Post
        I've heard that, as well as "they come in 5s, 2.5 is a half-step"
        That is correct
        1983 GS 1100E w/ 1230 kit, .340 lift Web Cams, Ape heavy duty valve springs, 83 1100 head with 1.5mm oversized SS intake valves, 1150 crank, Vance and Hines 1150 SuperHub, Star Racing high volume oil pump gears, 36mm carebs Dynojet stage 3 jet kit, Posplayr's SSPB, Progressive rear shocks and fork springs, Dyna 2000, Dynatek green coils and Vance & Hines 4-1 exhaust.
        1985 GS1150ES stock with 85 Red E bodywork.

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          #5
          Originally posted by chef1366 View Post
          That is correct

          So is a "step" 2.5 or 5? I'm hearing conflicting opinions.

          If I've got the 102.5's, then they could be either 4.5 steps or 9 steps, depending on who I'm asking.

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            #6
            What pipe are you using? 4-1 or a 4-2? Let's not call em
            "steps" call them sizes. If you're just using a non stock pipe, 4-2 I'd say you only need to go up two sizes. And you may not even need that. If you're using a 4-1 headed then maybe. But often,if you're using the stock airbox you don't need to up jet much for a pipe alone. The stock pipes flowed pretty good as it was, a jetting change for a 4-1 is often necessary because of back pressure changes. But I'd be surprised if you need more than two sizes up for a aftermarket 4-2 set up like a Mac or something.

            But to answer your question, 80 to 102 is 9 sizes. And that's much to much if you're using a stock airbox.

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              #7
              If it is really a "102" stamped on the jets then they are not Mikuni jets. And if they are not Mikuni jets then who knows what amount of fuel they will flow.

              I do have a 4/1 on my 550 and I run standard main jets, in fact all jetting is standard, and it runs fine. Although I believe the silencer is fairly restrictive and i have retained the standard airbox. As Josh says the most you will need for a pipe is 1 or 2 sizes up and maybe not even that. You will only know if you test at full throttle.

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