Need help with SBN 44 Pop Off
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  1. #1
    PWCToday Regular
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    Need help with SBN 44 Pop Off

    I recently rebuilt a sbn 44 and the pop off is way lower than it should be. I am running a 2.3 n/s and dull silver spring. This should yield a 20 psi pop off, but for some reason it is popping off at 13 psi. What could possibly cause this?

  2. #2
    Resident Guru JC-SuperJet's Avatar
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    Re: Need help with SBN 44 Pop Off

    Possible:

    You might have a 2.5 Needle Valve

    Might have mis-identified spring color/rating

    Spring may have been trimmed

    Fake inferior imitation Mikuni knock-off spring made in China

    The gauge is inaccurate; reads low

    Always wet Needle Valve top with Wd40 before each test
    Last edited by JC-SuperJet; 10-14-2018 at 06:28 AM.

  3. #3
    PWCToday.com Is My Home Away From Home john zigler's Avatar
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    Re: Need help with SBN 44 Pop Off

    Also is your n/s new? They can go bad, and leak. Is your needle arm height set level with the carb body?


    I am guessing you are testing dry, and it is just leaking some......
    RCJS also doing business as WATCON
    608-743-1305 9am to 5pm CST m-f
    email watcon@watcon.com

    Please visit our web sites

    new parts / products / services www.watcon.com
    used parts www.rockcountyjetski.webs.com
    thank you

    Please check out and like WATCON on Facebook

  4. #4
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    Re: Need help with SBN 44 Pop Off

    Quote Originally Posted by john zigler View Post
    Also is your n/s new? They can go bad, and leak. Is your needle arm height set level with the carb body?


    I am guessing you are testing dry, and it is just leaking some......
    Tested wet. Itís definitely not leaking. I will see how the arm sits this morning. I think all the parts came from you, they are brand new. My buddy ordered them, Iím just working on his ski.

    Quote Originally Posted by JC-SuperJet View Post
    Possible:

    You might have a 2.5 Needle Valve

    Might have mis-identified spring color/rating

    Spring may have been trimmed

    Fake inferior imitation Mikuni knock-off spring made in China

    The gauge is inaccurate; reads low

    Always wet Needle Valve top with Wd40 before each test
    As posted above, parts are from watcon, they are new, seat is labeled as a 2.3. It could possiblibly be the gauge but it seemed to be testing fine a couple weeks ago. Itís the digital gauge from Harbor Freight
    Last edited by roush611; 10-14-2018 at 10:08 AM.

  5. #5
    Top Dog Benflynn's Avatar
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    Re: Need help with SBN 44 Pop Off

    I'd test with old spring and n/s and see what I got, then would try and get changes I was looking for and then see. Also don't change out working parts, a carb almost never needs a whole kit

  6. #6
    PWCToday.com Is My Home Away From Home john zigler's Avatar
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    Re: Need help with SBN 44 Pop Off

    If the parts came from me, they are genuine Mikuni.

    Make sure you have the needle arm shaft seated correctly. I have seen them installed crooked, allowing them to sit high, and have low spring pressure.

    Also on salt water carbs, corrosion around the needle and seat "seat" area in the carb can be an issue.
    RCJS also doing business as WATCON
    608-743-1305 9am to 5pm CST m-f
    email watcon@watcon.com

    Please visit our web sites

    new parts / products / services www.watcon.com
    used parts www.rockcountyjetski.webs.com
    thank you

    Please check out and like WATCON on Facebook

  7. #7
    PWCToday.com Is My Home Away From Home john zigler's Avatar
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    Re: Need help with SBN 44 Pop Off

    If all else fails, install the carb and test run. Like stated above, you may just have a bad / inaccurate tester.
    RCJS also doing business as WATCON
    608-743-1305 9am to 5pm CST m-f
    email watcon@watcon.com

    Please visit our web sites

    new parts / products / services www.watcon.com
    used parts www.rockcountyjetski.webs.com
    thank you

    Please check out and like WATCON on Facebook

  8. #8
    Attention ***** PWCToday.com Is My Home Away From Home JonnyX2's Avatar
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    Re: Need help with SBN 44 Pop Off

    I would suspect the gage on the pump is off a bit.
    Quote Originally Posted by Firebird A/C&Heating View Post
    OMG.....Rules for 550 vintage ski class...550 ski riders do not conform to any kind of rules. That is why you are riding a 550 ski in the first place. Rules suck....
    PS...the rule book will be in my 550 pump
    Quote Originally Posted by WB1994
    Listen , stop your cryin' , its only an X2.

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