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  1. #1

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    Ultra 250 lacking on top end speed

    Hi everyone I live in the Midwest. I recently purchased two 2007 ultra 250x's. I bought them from separate owners. Each had about 40 plus hours and were in show room condition. The first one we bought did 70 mph from day one. It did it all the way up to winterizing and stowing away for winter. I took it out this weekend and could barely reach 60 mph. I heard an occasional miss at top end, noticed I only had two bar's on fuel gauge so I added more fuel and put a new set of laser plugs in it. Same thing. 60 MPH. Any thoughts? I am leaning towards bad fuel but, it doesn't spit or sputter, it runs solid just won't go over 60.
    The second one does mid 60's. I've read they run 65 -70 mph so I 'am not necessarily concerned about it but the other ski ran 70 mph all last summer. Un-tarped for first time and it barely hits 60. It probably only had a little more than a gallon or two of fuel in it over the winter. Thanks in advance for all suggestions.


  2. #2
    SuperCharged67's Avatar
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    Are you using a GPS or dream o meter?

  3. #3
    Gsmith88's Avatar
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    Have you checked the exhaust filter ? Think they need to be changed around 50 hours , may be longer , but it's a common problem for them to get chewed up and jammed in your exhaust

  4. #4
    nicjak's Avatar
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    its a 250 no exhaust filter lol

    Quote Originally Posted by Gsmith88 View Post
    Have you checked the exhaust filter ? Think they need to be changed around 50 hours , may be longer , but it's a common problem for them to get chewed up and jammed in your exhaust

  5. #5
    nicjak's Avatar
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    mate if you have done what you say above next step is to rule out a few other possible cause. as suggested a gps will rule out a jammed speedo wheel, best is to look at your RPMs on the fly at wot not the stored should be around 7600rpm from memory and also note the boost.

    if not since you have changed the plugs, i would remove the i/c and clean it check the s/c rotors with a mirror or bore scope, fog the s/c check the belt and tensions, i would also remove the fuel hose quick connect from the fuel rail and measure the fuel at the 3sec prime start up do it several times. should be at min around 88mls again from memory but with clean fuel filter can be upto 175mls. if all this is ok you should be good to go for the summer, also check all boost side hose clamps.

  6. #6

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    I was going off Kawasaki speedometer. This jet ski, when your doing 55, 60, 65 and go WOT, it try's to pull your arms out of socket. This weekend there was none of that. It rode and powered like our STX-15F. Nicjak, I will check all those things and let you know what I found. I will first need to research and bone up on those items. I haven't done a lot of ski work but I am mechanical. What is puzzling to me is when we parked it all was fine ?!? It has sat, outside, covered and on a ski lift. Thank you all for your time.

  7. #7
    nicjak's Avatar
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    water left in the water boxes in the lay up period could be your problem also fuel as you have said.

  8. #8

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    What damage would that have done to the water box's? I am guessing the boxes after the exhaust? I winterized very well but anything is possible?

  9. #9

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    I have thought about the fuel, but when I see bad fuel I usually think of fouled plugs, spitting and sputtering. There really wasn't much of that, except before I changed the plugs and even then it was extremely slight. You know I thought about a remark I made earlier, "it runs like our STX-15F". The only major diff is the turbo. So it made me wonder about the turbo? It has that turbo whine just not the body jousting torche

  10. #10
    nicjak's Avatar
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    the water condensates from the boxes back to the open valves on the engine where it then turns to nasty corossion and rust. maybe pull the s/c cover and check the pulley and belts condition. sounds like a number of things but not hard to rectify.

    oh another is check the air intake horn RHS sitting on the ski above the fueltank they drop out and suck to the side of the hull at wot.

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