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  1. #1

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    Ultra300x Rough Idle/Stall issue,,,

    Hello all,,

    Having an issue that came up with my 2012 Stock except SCOM Ultra300x. It hasn't been ran in over a month because attention was pointed towards a new boat I got... Anyway, took 2 tries but it started up, a bit of smoke upon startup like a 2 stroke, smelled rich. Idled fine out to the no wake buoy, went to open it up and it bogged down to the point of stalling, lots of knocking as well.

    It made boost during this time, and after, Managed to get it started again and it barely idled, really had to feather the throttle to keep it alive. Every once in a while it would open up and make boost, run ok for a second or 2 with no knocking sounds, then go back to its crappy self.

    Made it back in, pulled the plugs, rear one had some mild rust on it. Did a compression check, was spec across all 4 cylinders. Haven't gotten to do a leak down test yet. Really cleaned the plugs good, the rest were a sooty dry black/brown. Got them clean and reinstalled however it's still running crappy. I can sometimes get it to rev about 5k on the trailer but below that it wont stay running. I am assuming fouled plugs, although in my time I've managed to clean many plugs and revive them. I did order a new set. I am also going to drain whatever gas is in there and do fresh..

    The exhaust filter has less than 50 hours on it, was planning on replacing it next spring, however I don't think it would make it run like this... Also, when I do the leakdown I will check the fuel pressure..
    Any other ideas? Thanks for the assistance..


  2. #2
    Spooling's Avatar
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    Couple things to check:

    1. Check to see that your Tensioner is not seized:

    http://www.greenhulk.net/forums/show...=1#post2655153

    2. Check to see if your fuel filter is "flowing freely":

    http://www.greenhulk.net/forums/show...=1#post2805197

    3. A "not-so-good" scenerio is as shared here:

    http://www.greenhulk.net/forums/show...=1#post2837969

    Good Luck !!!

  3. #3
    "just sayin".. jetdave56's Avatar
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    If was running fine up to the point of not using for a month ?
    Yes fresh fuel and plugs but if still running lousy then the ex filter ,fuel primer test ,a seized tensioner would give you boost issues but practically stalling your ski hmmm can't see it though makes a good winter service to disassemble and grease the tensioner...

    My tensioner was totally seized and it ran fine though I decided to completely replace..

  4. #4
    Replace the Spark Plugs. JB

  5. #5

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    Thanks guys, All awesome information. Iíll pull it in the garage because as JetDave is noticing, working outside is not gonna happen today.

    Yes it was running fine up until I didnít use it for the past month. I didnít think of the tensioner because I removed it last year and re greased everything, but in that time frame a lot can go wrong again. Iíll check that first then do the leak down, then check fuel pressures and flow rate.

  6. #6

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    An update... Sparkplugs haven't come in the mail yet.. I pulled apart the exhaust and checked the filter, which was fine.

    The tensioner and idler pulley are smooth and free. The belt is also ok. While I had access to the driveshaft I also did a leakdown test and wasn't overly impressed. Cylinder #4 was good however 1-3 I could hear a very slight amount of air coming from the exhaust. The tool said it was within an acceptable range, however it's the harbor freight kit and also meant for car engines so I doubt the gauge is accurate for this sort of engine. There really should be no air escaping during the compression stroke.

    I do have a warranty left until 7/18 so I may be utilizing it. The only other issue is finding a Kawasaki dealer in NJ that has capable mechanics and not just over glorified parts changers..

    I'd like to put a boroscope/camera into the cylinders, however I can't find one with a small enough head to fit past these small sparkplug holes. Any suggestions? I want to buy one anyway just to have..

  7. #7

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    Thank you for all the replies by the way..

    Just had an Epiphany though and I'd like your input.. So it's been about a month as stated earlier since we took both of the Skis out. That day, about 20 minutes into the trip my 2003 12F Blew a coolant line and we had to turn back, and just made it thanks to the electric bilge pump.. Both skis were filled at the same time with the same gas at the same station, of which had just changed owners. After we got home I got some hose from NAPA and quickly fixed the 12F, but it was running crappy and continues to do so. It was smoking more than usual, barely idling, not running great up top either and there really wasn't a reason why. All checks came back normal, so I assumed some salt water got into an electrical connector and I just have been too busy to mess with it..

    Forward to the Ultra, it's pretty much running the same and smoking more than usual. It's a long shot but I can't ignore the fact that I have bad gas. I mean 2 skis doing the same crap.. If it looks like a duck, walks like a duck.....

    Now I gotta figure how to get the hose down in there to siphon...

  8. #8
    Take the time to smile sirbreaksalot's Avatar
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    hose goes in the tank easy enough ( 5/8 garden hose )

    otherwise its easy enough to remove the fill hose from the top of the tank ( I've never needed to )

    New Plugs & New gas you should be good in theory

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  10. #9

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    Got the tank drained and filled back with fresh trusted 93 octane... Still no change..... The last piece I haven't tried yet is the plugs, which should have been here by now but the jack ass seller on ebay took 4 days just to put it in the mail...

  11. #10

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    That's actually a really good idea..

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