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  1. #1
    novaboy's Avatar
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    Pilot jet questions

    I opened up the carbs last night for the first time for a 1998 GP1200. All 3 have a 1.2 N/S, shiny silver springs, but on carb1 it has a 100 pilot jet, carb2 has a 95, and carb3 has a 97.5 pilot jet. Should all three of the carbs have the same size jet or is this some what correct.


  2. #2
    Flying Scotsman's Avatar
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    Without looking it sounds right to me.

  3. #3
    novaboy's Avatar
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    What would the pop off pressure be for the 1.2 N&S and shiny springs? How would I go about trying to tune them with different jets? Wouldnt one be leaner then the others?

  4. #4
    staggered jetting is normal! pop off is high but the value isn't like 1.2 with silver spring the springs in the carbs aren't like in the kits so what I do is test pop off and make sure they are all the same

  5. #5
    also Oside has a good setup for this I think it's 100's across the board and 1.5 N&S I run it in 2 of my 1200's

  6. #6
    sleeplessnMS's Avatar
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    Novaboy, do ya have a pop off pressure gauge? I have the 48 BJ's mukini's and all the specs on springs I dont know what carbs ya have but the shiny silver springs are 12psi{65gram}.

  7. #7
    Moderator OsideBill's Avatar
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    On the 65U platform I run 1.5 N&S with 115gram(Gold) spring, 55 PSI Pop-Off, I run 100 Pilot jets across the board and 135 Main Jets. I have run Problem free since going to this set-up. I have raised compression, Boyesson Pro Reeds with stuffer's, R&D Power Plenum F/A and a Pro-Tec modified ignition. That's about it that I can think of right now.

  8. #8
    OLD # 7 IEGPR's Avatar
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    Hey Bill, why is OEM setup stagerd like that ??

  9. #9
    Pistonwash's Avatar
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    Quote Originally Posted by IEGPR View Post
    Hey Bill, why is OEM setup stagerd like that ??
    Yamaha felt like each needed different fuel requirements..notice the larger jet on the rear cylinder to help cool it better. The 65u engine was notorius for burning up the rear cylinder and had a myriad of crank problems back there because we had no "balancer" for the crank.

    Kawasaki had a balancer which smoothed out the vibrations..Yamaha tried different remedies for the problem.

    Jetting was one way to help cool the rear.

  10. #10
    Moderator OsideBill's Avatar
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    The compression in the cylinders was also staggered.

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