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  1. #1

    Question 2008 STX 15F Running Hot With No Warnings - Info Needed

    Hi All,

    I have just had a blown motor replaced with a motor from SBT. The motor seems to be running extremely hot but I'm not receiving any warnings from the ECU. The previous blown motor never ran as hot as this motor so I'm concerned.

    I have asked the guy that installed the motor and spoke with local Kawasaki Service Manager what the normal heat range for the motor. Neither guy had an answer when the ECU would trigger a warning.

    The temperature for cylinder head is 190+, manifold 180+ and various other motor areas 150+. I'm still in break-in period so I'm not running it more than 5000 rpm's. The technician checked every hose through out the cooling system and none are clogged. The water flow seems fine through the pisser and out the exhaust. The water in pisser is warm while riding but when switched off for a while and then on again the pisser water will burn your hand.

    So what should be the normal temperatures?

    What temperature should the Water temperature, Air temperature, and Oil temperature sensors warning occur?

    Even after the STX-15F has been off for more than 2 hours the cylinder head is still around 150+.

    So any help will be greatly appreciated. I can't afford another blown engine or technician fees.


  2. #2
    RLACEMAN's Avatar
    Join Date
    Aug 2011
    Random Lake WI
    This all sounds normal, water from the pisser will get much hotter after engine is off for a short time, cause it has more time to absorb the heat of the motor, as long as you have good water flow & the water coming out of the pisser while driving it doesn't burn your foot or hand, but is hot you should be fine. I burned my wrist once leaning on the valve cover while poking around the engine compartment just after driving it. For peace of mind you could also check out the temp sending unit to make sure it functions properly, I think if you cross the wires while it running your display should then show hot engine & flashing light, not 100% sure of this though, someone here with more electrical knowledge should know. If you shut this engine off at lunch time, it will still be slightly warm to touch at dinner time, there is a lot of metal in these 4 strokes, & they are well sealed for sound & to keep out water.

  3. #3
    RLACEMAN thanks for the input. However, the 190+ temperatures seems to hot to me. Yesterday, I went riding and rode it a little harder and the temperature was 204. Still no warning.

    Are there any other STX-15F owners that can check your temperatures of the cylinder head and manifold? It would greatly be appreciated!

    Do any of you guys work for Kawasaki? If so, would you find out at what temperature should the ECU show the warning.

    Much appreciated!!

  4. #4
    RLACEMAN's Avatar
    Join Date
    Aug 2011
    Random Lake WI
    Were you checking the temperature with one of those infared theremometer guns. I have one of those, if I remember when I go riding this weekend I will check the temp of mine to see what temps my 15f are at.

  5. #5
    Yes, that's what I used. That would be much appreciated!

  6. #6

    Join Date
    Aug 2009
    Shuswap lake, Canada
    I'll bet those are normal temps for a engine that have been developing significant power. But it'll be interesting to see what info comes back from RLACEMAN....I'm hoping he'll check the temp at a few areas around the engine to see what gets the hottest and what stays relatively cool.

  7. #7
    leejax01's Avatar
    Join Date
    Apr 2011
    Make sure the cooling line fittings at the waterbox and exhaust manifold are not clogged especially the one on the underside of the waterbox throat.

  8. #8
    Every cooling hose and fitting was removed and cleared as that was my first thought. But everything was fine and it didn't make a difference.

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