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  1. #1

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    Jul 2015
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    kawasaki ultra 250x low performence

    Heelooo greenhulk forum!

    I have been reading this forum for 2/3 weeks now. After i bought a kawa 250x. And i have som isjues i cant find any god answer to!

    Im gonna start from the beginning!

    When i first tried the ski it was realy slow. I max out at around 40mph and the ski just spun the hole time. Then i check the boost. Only godt 8/9psi..
    I did take out the oem intercooler for inspection! It was a disaster..
    The intercooler was leaking saltwater and the hole cooling ribs inside was "rusted" away.. yea its alloy but i didnt findt the right word!
    Soo.. i did remove the hole oem intercooler and i did make my own costum intercooler. This is a intercooler thats should flow enough air to suport a 6/700 setup! (I use to do cars!)

    I also remove the stock air bleed valve and did use the stock bov valve.
    I also did a impeller swap. From stock to solas 16/21 impeller.
    Pluss i did inspect the supercharger! It was fine!

    Then i tok the ski for another run. Now it was a hole new experience! The ski just hit the rpm limiter and throw the ski out of the water! I didnt check the speed with a gps but it was alot quicker than bifore.

    After a little more reading on these forum i did a gps speed test on my ski. On speedo it shows 112 kmh (65 67mph) but on gps i only got 60mph. And 7400 rpm!.. i know the speedo dosnt show realtime speed. But where is my last 5/7mph?! Are there a speed limiter on these skis?

    What is max rpm under load on these skis? I did read somewere it should get 7600/7800 rpm? Is this correct?

    I also had a big problem with water inn airfilterbox. So i did remake the intake so its getting air from the big rom infront! Thise did solve the problem. But i didn't get the last rpm. .

    This is a 250hp ski and my friends with 2 seedoo rxp 215 04mod and one gtr 215 15 mod. are going faster than i am... why?!. Is this just a slow ski or are im down on power?!

    And what is the best upgrade for this ski? Rideplate? Wedge? Impeller? Boost hp?

    I dont need to go 80mph. But i realy want to go faster than somone with 4 year older skis and 35 hp less!

    Thanks for any feedback! Regads from norway!


  2. #2
    IMy 250x ran 66 at 7,700 and 11, 12lbs of boost. Yours is down on power, speed and boost, sounds like it was abused and not well maintained at all.

    The 250 was THE best rough water ski ever built, its no speed demon and cant ever be made to be one. Its un fair to compare a glass, flat bottom ski like those donkies to the 250, it was made to do one thing, crush chop. Plates, grates, wedges, impellers add very little to a 250, if u saw 70+ out of one would be an achievement

    They do their best work in big water.

  3. #3

    Join Date
    Jul 2015
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    Yeah they do go faster in som ruff sea.
    But. When driving in som chopy sea all the waves are going over the ski and hit u inn the face.. it wont even try to put the waves underneath! its impassible to drive and not get wet!?

    Maby this will work better with 1.degrees wedge?! But i cant se how mutch better this wil be.

    I see my freands with seadoo. Offcorse they also get wet in ruff sea. But it dont lock that bad.

    Ennyhow. Whats the best uppgrade for this ski?

    Exept by a new 310r!..

    If its allmost no diffrent.. i think i will sell this and by a seadoo..

  4. #4
    nicjak's Avatar
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    you have changed many things that could be causing your issues and to add insult it sounds like the ski has had a very hard life, fit the stock prop, check the fuel system, valve clearances, you need to start from scratch, how do you know it has no heat soak from your home made i/c?

  5. #5

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    I will check the air intake temp tomorrow. But i dondt think thats the problem. I have redirected the water to intercooler so theres only cold water entry not hot and cold like it is on stock ic. I also did bor out a bigger hole in the water inlet from the pump. So it will deliver more water. But i have nevere testet iat. I do that tomorow!


    Never open the engine. But it sound all fine. No ratling ect from engine itself and it do go on all syl. I will however do a compression test to morrow just to be sure!

    What rpm shuld i have with a solas 16/21 impeller? This is however the impeller solas themselves says its the best impeller for stock/easy modded ultra 250.

  6. #6
    U really need to ride the 250 with authority in the rough, the harder you ride the more you will be rewarded, you'll leave the donkies in your wake, yes they are a wetter ride than the flat bottom skis you ride with.

    without any trim, the 250 with a wedge and a riva plate will ride higher and dryer, but you'll lose some rough water hookup and handling. never cared for the riva plate on my 250, but it was good for 2 possibly 3mph with a wedge, and a solas, and got 68-69 out of it. you can do free air mods, remove the right side water box, timing plate mod, and everything else under the sun, like I said, 70s are an accomplishment with it, but at what cost ????

    a stock scommed 310 will do 72-73 out of the box, with some free mods, and a few aftermarket bolts ons it should do 74-75. its more playful, feels lighter, narrower and rides higher in the water than a 250 and with only a scom should beat the donkies in everything but the flattest of water...

  7. #7

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    Jul 2015
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    Thanks!
    Stop talking about the 310r! its out of my leage! haha.

    Im in som free exhaust tuning! and i did take both water box out today and i realise the left box its mutch more restrictive than the right. So i guess i just going to put the right waterbox inn again! and make som coustum tubing on the leftside over to the right with no water box on the left side.

    I also did remove the rubber end inn the exhaust outlet. Hopfully all this will gain 1 mph!

    1 mph here, 1 mph there!

  8. #8

    Join Date
    Jul 2015
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    13
    Thanks!
    Stop talking about the 310r! its out of my leage! haha.

    Im in som free exhaust tuning! and i did take both water box out today and i realise the left box its mutch more restrictive than the right. So i guess i just going to put the right waterbox inn again! and make som coustum tubing on the leftside over to the right with no water box on the left side.

    I also did remove the rubber end inn the exhaust outlet. Hopfully all this will gain 1 mph!

    1 mph here, 1 mph there!

  9. #9

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    Jul 2015
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    Where can i get a 2 degree wedge for ultra 250x? I can only find 1 degree plate?!.

  10. #10
    nicjak's Avatar
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    from 2007/2008 oem ultra lx

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