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  1. #1
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Kawasaki 4 stroke conversions out there?

    I was just curious about this, seeing as everyone who does a conversion here seems to use a SHO motor or 4-Tec motor I was wondering if there is a reason no one uses the ultra motors or the 15f style motor seeing as there is a pretty considerable amount of common parts between the ski motors and the ninja motors. Is the difference weight or just cost? Also has anyone ever converted a first gen ultra 150 to a 4 stroke S/C or is the hull too small?

    Sean


  2. #2
    mrbtd's Avatar
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    The reason has to be the lack of HP.

  3. #3
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    That's kinda what I figured But the 250 and 260 motors are on par if not more powerful than a stock 4 tech right? the rxp x has 255 if I'm not mistaken? Do they just weigh more?

    Sean

  4. #4
    Hydrotoys's Avatar
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    Cost, lack of stock skis to pull from, size of engine, lack of sharing between builders, lack of builders, lack of aftermarket, and finally the roots charger which limits how far you can go with this engine. 250 may be the number, but the rotax build ups fly past this with ease on 91 oct and do it without a problem.

    I'm all for it, and almost did a 250x into a 15F hull with my local dealer, but decided against it, by applying some of the above reasons... besides that, the Ultra250 is an awesome rough water ride. It seems like a shame to rip one apart to do a conversion.

  5. #5
    thesepaperwings's Avatar
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    There have already been 250/15F conversions. Skip even had a 250 top and motor with a 15F bottom.

  6. #6
    Hydrotoys's Avatar
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    Yup, but us mere mortals still don't have a way to do it, or any instructions how.

  7. #7
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    I saw that one it was cool but way over the top for me. I was actually thinking more along the lines of a ultra 150 hull with a meaty 4 stroke in it, but I really don't know all that much about the ultra hull.

    Sean

    I was also wondering if the stxr and 12/15f share motor mounts because if they do then the old ultra should as well meaning that you could drop a built 15f stroker motor into the ultra hull.
    Last edited by smokeysevin; 02-28-2009 at 09:00 PM. Reason: I forgot what I meant to say

  8. #8
    jtskir15f's Avatar
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    it still seems like a lot of work for a 4stroke U150. Just throwing a 15F motor in there without giving her some boost won't make all the work worth while.

  9. #9
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Yeah, I have no intention of just doing a stock 15f I was considering doing an offset ground crank with a mild overbore and zx12r camshafts along with zx throttle bodies I want to build up the kawi platform as much as a broke college student can without going to boost, I really don't feel like messing with a boost gauge.

    Sean

  10. #10
    jtskir15f's Avatar
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    ik what ya mean. where ya goin to school at? i'm a freshman at Marquette in Milwaukee.

    thought about turboing the 15F but i dont know any good tuners in my area

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