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  1. #1
    I dream skis Mr Noisy's Avatar
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    Trying to setup dual 38 carbs for very hot 650 X2!

    Hey guys.

    im speaking to you from the uk

    so, I have this x2, it's been a PITA for the few months I've owned in, various mechanical faults, I'm now on engine build 3 and I think it lean seized the other day so now I need to tear it down again.

    i won't post pics of the damaged bore at this time but if it helps I will.

    anyway so I finally get the ski running properly a few weeks ago and it's like a bat out of hell, absolutely delightful throttle response from idle to flat out, so crisp I couldn't believe it and no hesitation at all.

    plugs looked reasonable so it's well tuned and working I'm thinking. I was happy.

    then on day 2 I was WOT for about 20 seconds and I felt something go bad, so I slowed down and pulled in, thought I had maybe fuel starved so I filled up but then it wouldn't restart.

    after lots of messing about finally got it going but it wasn't right, sure enough, no compression on rear cylinder.

    being on dual carbs, I suspect a carb fault.

    i am running bn38s



    the spec of the motor is

    westcoast stacks
    bn38 duals
    westcoast inlet
    stock bottom end
    weetcoast ported cylinder
    pjs head
    westcoast header
    coffmans pipe
    pjs water box
    jetinetics total loss

    heres some pics







    anyway so I opened up the carbs for the first time last night

    both were basically the same with popoff at around 8 psi but the rear carb had a Viton needle so it sealed all the way up to a crisp pop whereas the front carb leaked from 1psi onwards with no real pop

    needle and seats are 2.0

    Main jets are stamped 10

    i will need the help of a round body expert to tell me what the 10 stamp means, I think it might be 0.10mm but I don't know

    Most of you guys talk about jets being 120s or 150s etc

    does that mean 0.120mm etc??

    which means might might have 100s, which is ok running dual I guess

    high speed screws were 1.5 turns

    low screws were 1.0 turns



    i really really hope some of you guys can help me please, I don't really know why it seized if it ran so good, also I don't know what you will make of the carb setup

    any help really is appreciated

    love from rainy England

  2. #2
    I dream skis Mr Noisy's Avatar
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    Re: Trying to setup dual 38 carbs for very hot 650 X2!

    ok just had another look

    got my small drill bits out

    main jets in these carbs are 1.00mm and stamped 10

    i would really like to know if dual carbs at 1.00mm is approx jetted correctly

    and for reference, if someone talks about a "120 jet" does that mean 1.20mm???

    needle and seat are confirmed both at 2.0mm

    do these seem to be approx correct for duals?

    it did run real crisp in the low end so id guess the N/S were approx ok, popoff was around 8psi on both but the front cylinder N/S was leaking, the rear was not

    it is the rear cylinder that seized, i wonder if that was something to do with it?

    thanks, sam

  3. #3
    PWCToday.com Is My Home Away From Home fastgtfairlane's Avatar
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    Re: Trying to setup dual 38 carbs for very hot 650 X2!

    i wouldnt waste anymore time with the bns.. no way to konw what the jet orfices are.. i bought a new set of sbn 38s on ebay for about 76 per carb... then you can easily change jets.. if you go too big on drilling the orifices you cant go back... sounds like you had a lean seizure..
    91 440; PJS Viper 7000, jetsport exhaust mani, factory full pipe, coffman waterbox,solas 17*, jetco worked 440 pump, ocean pro nozzles. shredmaster ocean rideplate and grate combo, wide tray, footholds, deep strake mod, driveshaft fill,650sx quick turn

    build thread part 1: http://www.pwctoday.com/showthread.php?t=331343
    build thread part 2: http://www.pwctoday.com/showthread.php?t=364872
    build thread part 3: http://www.pwctoday.com/showthread.php?t=396154

  4. #4
    I dream skis Mr Noisy's Avatar
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    Re: Trying to setup dual 38 carbs for very hot 650 X2!

    The mains are 1.0mm, that's confirmed!

  5. #5
    Top Dog MJSelf's Avatar
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    Re: Trying to setup dual 38 carbs for very hot 650 X2!

    Quote Originally Posted by fastgtfairlane View Post
    i wouldnt waste anymore time with the bns.. no way to konw what the jet orfices are.. i bought a new set of sbn 38s on ebay for about 76 per carb... then you can easily change jets.. if you go too big on drilling the orifices you cant go back... sounds like you had a lean seizure..
    X2

    Bn carbs are great for stock skis.
    Sbn set up is way better for all the performance parts you are running.



    Sent from my iPhone using Tapatalk 2

  6. #6
    I dream skis Mr Noisy's Avatar
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    Re: Trying to setup dual 38 carbs for very hot 650 X2!

    Gahhhh, not what I'm wanting to hear!!
    Last edited by Mr Noisy; 07-19-2014 at 11:14 AM.

  7. #7
    I dream skis Mr Noisy's Avatar
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    Re: Trying to setup dual 38 carbs for very hot 650 X2!

    Although I must say, do people not give up too easily with the BN?

    Carbs are not THAT easy to source in the UK, nor are the particularly cheap.

    Im confident I can dial these guys in as long as I'm in the right ball park!

  8. #8
    PWCToday.com Is My Home Away From Home Dencaddie's Avatar
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    Re: Trying to setup dual 38 carbs for very hot 650 X2!

    There is a reason not too many people run BNs anymore and especially dual BNs. 3 motors aren't enough pain. Buy a single SBN44 or 46 set-up and ride instead of wrenching.
    90 SN - Short Rockered Project Ski
    91 SN - 735 GroupK B-Piped Frankenstien
    92 X2 - HPT Ported 650 with most of the goodies
    94 WB1 - 62t JetPro Piped Weeble Wobble - sold
    95 WV - Family Ski

  9. #9
    PWCToday.com Is My Home Away From Home fastgtfairlane's Avatar
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    Re: Trying to setup dual 38 carbs for very hot 650 X2!

    the fuel pump isnt very strong on them and with modified engines the signal is weaker than a stock engine.. plus with the sbns that have changeable jets, you can take the carbs off and run them on a completely different engine just by changing the jets and n/s springs and such.. and they have a much better fuel pump than the bns.. look on ebay.. i bought mine basically new on ebay for 76 bucks plus shipping...it was like 180ish for both of them
    91 440; PJS Viper 7000, jetsport exhaust mani, factory full pipe, coffman waterbox,solas 17*, jetco worked 440 pump, ocean pro nozzles. shredmaster ocean rideplate and grate combo, wide tray, footholds, deep strake mod, driveshaft fill,650sx quick turn

    build thread part 1: http://www.pwctoday.com/showthread.php?t=331343
    build thread part 2: http://www.pwctoday.com/showthread.php?t=364872
    build thread part 3: http://www.pwctoday.com/showthread.php?t=396154

  10. #10
    PWCToday.com Is My Home Away From Home hellcat66's Avatar
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    Re: Trying to setup dual 38 carbs for very hot 650 X2!

    yeah, that clown looks sad cuz you're running those bn's...quit fukking withtthem and get a single 44 sbn, you will be glad you did!

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