650SX Pump and Manifold Questions
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  1. #1
    PWCToday Newbie
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    650SX Pump and Manifold Questions

    Hello all,

    I have been working on my 87 650 SX and ran into a few areas where I could use some advice.

    Problem One:
    I rebuilt my jet pump with new bearings yesterday and when I put it back together it was not turning as easily as I had hoped. It appears the second o-ring makes contact in the spacer and causes friction. After taking the impeller off I looked for any issues and couldnt find any. Today I was told new pumps can be a little stiff so I decided it must not be a big deal and put the impeller back on. Once I re-install the impeller I find it only binds up before I can torque it. I removed the impeller again and sanded smooth any contacting surface, coated it with fogging oil, and it still binds up.

    Could this heat wave be the issue? Did my pump warp overnight?


    Problem Two:
    Im adding a 44SBN carb to the ski and already bored out the intake to 44mm. I will purchase the needed parts to make the carb work but im more focused on the exhaust manifold. My friend who owns a machine shop is worried about breaking through the water jacket and didnt want to mess it up on me. I saw a few posts of people leaving the exhaust alone and others going with an aftermarket manifold.

    I am trying to minimize cost and not buy an aftermarket manifold but I need a properly set up ski to run correctly. What is the general consensus?


    Thank you for your imput

  2. #2
    PWCToday Regular Pb300's Avatar
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    Re: 650SX Pump and Manifold Questions

    If you are using the stock 1987 650sx exhaust manifold, those can only be bored out so much. The 1987 manis are have a smaller ID than later years too but I am not exactly sure on the extent of how much each manifold can be bored out before compromising the water jacket. Someone else who is more of an expert will comment.

    Perhaps go with an After Market mani and you will not have any worries. Just my thoughts. I know you said minimizing costs but maybe you could find a larger stock manifold and bore it out more than what you can do with your current. Assuming you have a black manifold, measure the ID and then check on here for a silver manifold but verify the ID in that is larger before assuming. The silver manifolds I've come across are always larger in my experience and are from later model skis but I have read that you need to verify before assuming that because it may not always be the case.
    Last edited by Pb300; 07-03-2018 at 08:43 AM.

  3. #3
    PWCToday.com Is My Home Away From Home hyosung's Avatar
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    Re: 650SX Pump and Manifold Questions

    did you put the spacer tube between the bearings in the pump ?/
    i belive there is an adaptor to use the bigger carb with the correct bolt pattern
    Last edited by hyosung; 07-03-2018 at 08:55 AM.
    http://www.pwctoday.com/showthread.php?t=425767

    modded X2 650

    900 powered custom 650 sx .

    Jerry Rigging is my specialty .....



    if i did like everyone else and copied everything i needed or wanted i would save lots of time and money.

  4. #4
    PWCToday Newbie
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    Re: 650SX Pump and Manifold Questions

    I did use the spacer on the pump, and I ordered the adapter plate for the carb.

  5. #5
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    Re: 650SX Pump and Manifold Questions

    -There is another spacer that slides onto the impeller shaft before the impeller goes on, make
    sure that is in place or the pump will bind.
    -The later year 650 exhaust (1991+) manifolds are silver and have a 42mm output along with a exhaust diverter bridge just like the aftermarket manifolds. They work very well.
    2001 Superjet; R&D, Blowsion, UMI, Riva, Wetwolf, Ocean Pro.

    1987 650sx: Mariner, UMI, Neo Designes, R&D, Jetsports, Renthal, Hydro-Turf, Skat-Trak, Reworked stock pipe, 40mm carb, Wetwolf F/S cone.

    1986 JS300; lots of mods, fast for a 300...I think

    1987 X2: Rips pretty good and has some 80's flare.

  6. #6
    PWCToday.com Is My Home Away From Home hyosung's Avatar
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    Re: 650SX Pump and Manifold Questions

    ? did you use the same impeller there are 2 different types big and small hub.not sure what the outcome would be by trying to interchange the 2 as i have never tried it.
    aside from that and the spacers ,you may have to remove the bearings and do some measuring to find where you are getting binding from
    Last edited by hyosung; 07-03-2018 at 11:17 AM.
    http://www.pwctoday.com/showthread.php?t=425767

    modded X2 650

    900 powered custom 650 sx .

    Jerry Rigging is my specialty .....



    if i did like everyone else and copied everything i needed or wanted i would save lots of time and money.

  7. #7
    Resident Guru bored&stroked's Avatar
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    Re: 650SX Pump and Manifold Questions

    What does the exhaust manifold have to do with adding a larger carb?
    '90 Superjet: ported 760, dual 44's, B pipe, ADA head 190psi, TDR waterbox, hooker 10-16, sponsons. Wife's ride
    '94 Suuuperjet: 84mm 61x, ported, protec pipe, H2o designs waterbox, Newmiller head 175psi w/girdle, protec ride plate, Protec mod'd cdi, UMI grate, RN pole -4", rev footholds, solas prop, sweet green turf+wrap.
    '95 Raider 701: Fiberglass not SMC, Hydrotrailer hitch, ugly purple and yellow everywhere.

  8. #8
    PWCToday.com Is My Home Away From Home hyosung's Avatar
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    Re: 650SX Pump and Manifold Questions

    Quote Originally Posted by bored&stroked View Post
    What does the exhaust manifold have to do with adding a larger carb?
    a quick lesson it mechanics of the internal combustion engine :
    air in it has to come out , the better fuel and air comes into a motor the better it needs to be expelled """hence OP wanting to adjust the exhaust exit".

    does that answer your dumb question."
    http://www.pwctoday.com/showthread.php?t=425767

    modded X2 650

    900 powered custom 650 sx .

    Jerry Rigging is my specialty .....



    if i did like everyone else and copied everything i needed or wanted i would save lots of time and money.

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