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  1. #1
    just GOT TO DO IT! great lakes gpr 1200's Avatar
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    group k 1390 owners help!!!!

    Hey I'm getting a lot of bottom end lag. I'm wondering what do you have you low jets set at?


  2. #2
    ABBOTT's Avatar
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    what is your pump year and prop pitch??

  3. #3
    just GOT TO DO IT! great lakes gpr 1200's Avatar
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    2002 pump. 14/20 concord impeller. top rpms are 7220

  4. #4
    philip_gpr's Avatar
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    any chance you can be more specific

    is the ski bogging down?

    or does it "fall flat on its face"

    at what rpm is this happening? at idle? at low rpm? at mid? etc etc

  5. #5
    just GOT TO DO IT! great lakes gpr 1200's Avatar
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    It Idels great. but when you nail the thottle it boggs down for a bout 2.5 secs until it hits 4500 rpms then rips.high end is good, it feels a lean, I JUST PUT THE carb rack on with new hoses, I left the jetting where it was put.by group k. the water was real cold, 57 * and permix was 28:1. going to 32:1 today. then we will see. I didn't want to mess with it,because group k set them. I was just curious where every on other is,

  6. #6
    Like a chimp with a ball-peen hammer smackwave's Avatar
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    I think my carbs came back pretty rich, 2 turns out on bottom and 2 on top. I've been turning the low end screws in 1/4 or 1/8 at a time to 1 1/4 (hate getting to those things) and the plugs are still reading rich on bottom. I think the combination of your premix ratio and the richness are causing your problem.

    And run, do not walk, to your favorite online vendor that sells the Advent T3 and buy one. It won't help you with this issue specifically, but the larger bore size needs that additional advance, and your ski will thank you.

  7. #7
    ABBOTT's Avatar
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    this may sound like a dumb thing to ask - but if you get a chance, look at your fuel filter and double check that it's clean. Sounds like its starving for fuel at a certain range of rpms. Just my guess - hell i could be way off.

  8. #8
    just GOT TO DO IT! great lakes gpr 1200's Avatar
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    [quote="ABBOTT"]this may sound like a dumb thing to ask - but if you get a chance, look at your fuel filter and double check that it's clean. Sounds like its starving for fuel at a certain range of rpms. Just my guess - hell i could be way off.[/quote



    Yes I have new filters . I put in a duel feed while I was down there.

  9. #9
    GPRPITMAN's Avatar
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    what carbs? what size jets? what size spring? how many turns out on the highs? how many on the lows? Is your prop stock out of the box or re-pitch?

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