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  1. #1

    2006 stx-15f problems ???questions??? piston failers

    Hello my name is Kerry and just became a member of the site, looks to be the place to go for information and great people.

    now to work, i purchased a 2006 stx15f with 28 hours on it bike sat for 2 years with no use, i purchased put new battery changed oil and went to the water. started great and idled fine made a pass or two in the bayou (yes im from Louisiana LOL) bike still ran quite, went to get on top again and it jumped right up then started to boooggggg let go gas and it wouldnt idle, pulled number 2 plug and noticed it had been beat up. removed engine to find what appeared to have been a piston ring land failure and it must have traveled through the intake to other cylinders ?? but i find it strange that all pistons failed in the same place on intake side? is this normal or is it just from the trash going in at that point or is this caused when water is sucked into cylinder?????

    The big question here is ?? is this a good engine in its natural aspirated form and with oem pistons or should i be looking at upgrading to JE pistons or is this engine known to have trouble? Im not looking for performance just a good reliable ski.

    Thanks KerryClick image for larger version. 

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  2. #2
    also have questions about how much water should be coming out the bypass outlet(piss hole)? should it be spraying for with pressure ? when i ran mine the day it failed pistons it was only a little water coming out? by no mean with lots of pressure. I only ran it for like 5 minutes, 2 runs about 100 yards and some idling at boat luanch? would that have been enough time to fail the pistons due to over heating? also would it have thrown an alarm or warning? it never had a alarm or warning light or buzzer?

  3. #3

    Join Date
    Sep 2006
    down under
    Maybe it didn't like 2 yr old fuel???

  4. #4
    yea he told me he had just got it serviced but while running it , i noticed the smell of old fuel. may have been the fuel that got me???

  5. #5

    Join Date
    Sep 2006
    down under
    Id say that old fuel caused plenty of deto and fooked your engine.

    15f's are generally very reliable and there are no issues with the stock pistons. (in a stock ski)

  6. #6
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
    Join Date
    May 2008
    I have never seen that on a 15, melted pistons from a bum fuel pump but never cracked ring lands. Just get the replacement pistons, you can get new rings from JE for cheaper, I will look up the part number.


  7. #7
    thanks for the comments i just ordered pistons and rings with gasket kit
    will flush the tank of coarse lol

  8. #8
    That kind of 15F piston failures can happen in a "perfect storm" condition - minimal cooling capabilities with old/bad fuel having really low octane level resulting in excessive combustion temperature.
    It's not a common problem at all on 15F but seen it happening a few.
    I would stick with OEM pistons.

  9. #9
    thanks for the comments, I found a set of stock pistons with 19 hours on them, im gonna stick that back in and see what happens? Is there any cooling pump or anything else i may need to check, ???

  10. #10
    Cooling - Check/clean out the cooling water jacket/passages in the cylinder with a pick and then suck out the debris with vacuum cleaner. After engine is assembled, disconnect the inlet cooling hose at the transom and blow compressed air into the hose. And then reconnect the hose and run the engine with garden hose water to clean out.

    ECU - You may have an earlier version of ECU P/N 21175-3731 which number is stamped on the ECU. If you can afford, try a later/current version P/N 21175-3737 which has slightly different ignition timing to help preventing detonation.

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