650/X-2 Mikuni sbn 44 jet size?

Discussion in '650/X-2' started by msutherland, Aug 2, 2012.

  1. msutherland

    msutherland

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    I just ordered a Mikuni sbn 44 for my sons 1990 650sx. Does anyone know what size jets are recomended for this carb/ski set up? Its a completey stock ski. We have a new manifold ordered to fit the new larger carb and will upgrade the prop at some point but no engine mods.
  2. parky07

    parky07

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    im running 115 low 145 high and 2.0 pop off with a westcoast pipe/manifold
  3. whooiedog

    whooiedog Gold Member Site Supporter

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    if its all stock
    start with 100 low jet
    130/140 high jet
    2.0 N/S
    80 gram spring (black in color)
  4. N2 H2O

    N2 H2O Previously Tbone550

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    I would start with 110 pilot, 140 main, 2.0 n/s, and 80g spring. It might be a little rich, but I'd rather start rich than lean.
  5. iangdesign

    iangdesign Cats, lots of cats!

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    150 high 115 low and 2 gram n/s and silver spring was my magic number.
  6. Byeai

    Byeai "Cheetos-Man"

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    How many turns out

    Sent from my SAMSUNG-SGH-I727 using Tapatalk 2
  7. runrider

    runrider

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    bump. I have same question.
  8. parky07

    parky07

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    I think ine are 1 turn low 1.5 turns high
  9. runrider

    runrider

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    What jets should I try? I have 175 compression, coffman pipe, stock non-drilled waterbox. (44sbn carb + 44mm intake)
    I'm thinking around 115 & 150, based on other responses here, but I really have no idea how to choose.
  10. parky07

    parky07

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    120 low 145-147 high 2.0 n/s Silver spring is what I would go with
  11. Dutchie

    Dutchie

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    Hey,

    Does anyone know this:

    1: If the O rings on the HS and LS are bad, what are the symptons ?

    2: How much play is there in the screw adjustment. Like if I have a 120 LS jet and I turn the LS screw out, does this have the same effect like i have a 122 jet with a turn? ( hope you understand)

    My x2 650 westcoast pipe set, 44 mm mikuni intake set boggels in lower rpm until it rev's up. Like it's way to rich.

    Strange thing is that I put the set on my ski and the ski ran fine for an ouhr or so. Then my exhaust coupler was to lose and came off. The ski ran like crap and i started turning the screws ( not knowing the exhaust was off... )
    After fixing the exhaust it ran better again but stayed boggeling only in the lower rpm the like in the whay when the exhaust was off, strange.. If My jets are to big it should not have ran so good the first ouhr..

    (I also took the hood caps off to see if it had to get more air, did not help.)

    My setup is :

    Stock 650
    Westcoast many
    Westcoast Pipe
    Westcaost intake 44mm
    44mm Mikuni
    PROK flame arrestor
    Low jet 120
    Main jet 140
    LS: 1 turn
    HS: 1.5 turn

    (Bought frome steve and shipped it out to holland ! :p )

    Greetings,
    Last edited: Sep 2, 2012
  12. Dutchie

    Dutchie

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    Took the carb apart, looked good.

    Renewed the Orings, and give the spring more pressure. Ran good again so i think the o rings where the problem.

    Turned the LS and HS in a bit and now it had perfect response, brown sparks at 1\4 2/4 3/4 and WOT trottle.

    Im pleased now, jetting is the same as i had it befor, it was not rich at all.

    Hope this will help someone else.

    Greetings,

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