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  1. #1
    crxski's Avatar
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    Jetting for Flame arrestors and milled head 787cc

    Just want to confirm this setup


    I pulled this off the website from the shop that's milling my head. Does it sound right? Need to confirm before I go buy some new parts.


    One this there is no mention of pop of pressure?




    (jet kit includes 90 pilot & 170 main jets & (2) 2.3 needle & seat)
    (lows 1 & 1/4 turn out on both)
    (mag high 1/4 turn out / pto high 1/2 turn out / add 1/4 turn on both for 175 psi)
    (all settings tuned for outside temp of 72 F / warmer and humid air requires less fuel so turn adjusters in slightly)


    http://www.engine-tech.com/shop/prod...products_id=37


  2. #2

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    75 piolets, 145 mains, 2.0 N/S, 65 gram springs, 1 1/4 LS, HS PTO 5/8, HS MAG 1/2-- perfection for Michigan-- others down south recommend 80 gram springs and 142.5 mains-- try both...

  3. #3
    I run 75 ls 145hs mag, 147.5pto. HS adjusters closed. I use stock needle and seat with 65g springs. I have aftermarket flame arrestors, and 170psi compression. Jetting is great for my set up.

  4. #4
    crxski's Avatar
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    What is your guys altitude? I'm at around 500ft.

    If I could run stock needle and seat then that would save some money but I really haven't heard of people doing that, most seem to run 2.0

    So does the pop off stay the same as stock then?

  5. #5
    I have been running the stock needle and seat for 4 years. The jetting in your original post, was for the 951 motor.

  6. #6
    785xp's Avatar
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    If you read the website closer, that is his recommendation for a 951, go down the page a little lower for the 787:

    (jet kit for just F/As are 80 pilot jets/stock 142.5 main jets/
    2.0 needle & seat with 3/4 turn out on both lows & 1/2
    turn out on the MAG highs & 3/4 turn out on the PTO highs)
    (warm/humid climates above 72F could require 75 pilots with an additioanl 1 half turn out on all adjusters)




  7. #7
    785xp's Avatar
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    On my wife's 787 GTX, I am using 75 pilots, 2.0 needles and seats and 3/4 turn out on both lows & 3/4 turn out on the MAG highs & 7/8 turn out on the PTO high.

    Now I haven't had a chance to test it in flat water yet and do some plug chops. Hopefully before the end of the summer.

    Now on my 1996 XP, I had them set up by a well known Seadoo engine builder back in 1997. We started off using the 80 pilots that R&D recommended but they didn't work. I know we didn't change the needles and seat, but I think he made some other adjustments. Back then I trusted him to set it up and I have been happy with it since so I haven't even had it apart. I am running the R&D Power Plenum on it.





  8. #8
    crxski's Avatar
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    Quote Originally Posted by 785xp View Post
    On my wife's 787 GTX, I am using 75 pilots, 2.0 needles and seats and 3/4 turn out on both lows & 3/4 turn out on the MAG highs & 7/8 turn out on the PTO high.

    Now I haven't had a chance to test it in flat water yet and do some plug chops. Hopefully before the end of the summer.

    Now on my 1996 XP, I had them set up by a well known Seadoo engine builder back in 1997. We started off using the 80 pilots that R&D recommended but they didn't work. I know we didn't change the needles and seat, but I think he made some other adjustments. Back then I trusted him to set it up and I have been happy with it since so I haven't even had it apart. I am running the R&D Power Plenum on it.

    ooh ok so I was reading the wrong one...good thing

    so using 75 pilots should be fine and 142.5 main jet should be fine with a 2.0 n/s?

  9. #9
    785xp's Avatar
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    You should be fine, but make sure you do a plug chop and inspect the color of the plugs.

    Have you changed your internal carb fuel filters and fuel lines yet? You want to make sure you have a good flow of fuel to get proper readings.

    Thinking about it, I can't remember if I changed the springs in the GTX as well. Maybe someone else can comment on this setup.

  10. #10
    crxski's Avatar
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    Quote Originally Posted by 785xp View Post
    You should be fine, but make sure you do a plug chop and inspect the color of the plugs.

    Have you changed your internal carb fuel filters and fuel lines yet? You want to make sure you have a good flow of fuel to get proper readings.

    Thinking about it, I can't remember if I changed the springs in the GTX as well. Maybe someone else can comment on this setup.

    Thanks for the quick reply, I'm going to ask him about the pop off pressure when I get there. I already cleaned the fuel system and replaced the fuel lines. Carbs where stopless basically, alittle bit of junk in the filters though. I think I messed something though after cleaning because I lost 150/200rpm topend. When I put the jets in I'll check everything over ones again to make sure.

    And I'll forsure check the plugs, just have to make sure its a calm day.

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