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  1. #1

    what caused this damage to the piston???

    recently bought my very first jet ski a 2000 sea doo xp. ran super the first few times i took it out but the last time it all of the sudden developed a miss,wouldnt idle and would take forever to get up and go. so i looked at the sparkplugs and they were very black with alot of soot so i changed them and tried to test it the next day and it wouldnt crank. it still has the tempo fuel lines which i have read so much bad stuff about so i checked the internal fuel filter in the carbs and they were clean. pulled the rave valves and noticed one was wet with a lil carbon and the other was dry with alot of carbon build up. peeked thru the hole and looked at the top of the piston and didnt like what i saw so i pulled the top of the head off and was astounded at what i saw! any ideas about what could have dented the outside of the piston like this?
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  2. #2

    Join Date
    Jan 2006
    Patterson La
    Broken ring, or piece of a bearing from the bottom end. You are LUCKY. You caught it early, and you can rebuild it relatively cheeply now, rather than if you had waited until the piston cracked, or the rod broke. The cause could have been water injestion siezing the piston, and then running it until a ring snagged in a port and became lodged in the combustion chamber. Or you could have had a piece of bearing cage get in the top of the motor. Your crank might be good, but its time for a full tear down.

  3. #3
    whats ur idea of cheeply? i was thinking of just putting a new crate motor in. i know nothing of jet skies and not much more on two strokes. the guy i bought it from couldnt tell me much about it . when it was serviced last or how many hours it had.i think he bought it and raised the price to make a quick buck.

  4. #4
    caliburn's Avatar
    Join Date
    Aug 2012
    Sister lakes Mich
    you tore into it this far keep going and see what the issue was then you will have your decision made for rebuild or crate, let us know

  5. #5
    im prolly just going to go crate. everytime i try to save a li money it always ends up costing me more lol

  6. #6
    If i knew,...I wouldn't ask sea-one's Avatar
    Join Date
    Aug 2009
    From my experience, thats usually caused from a thrust washer on the crankshaft or a rod from the bearings failing due to improper winterizations most likely IMO

  7. #7

    Join Date
    Jan 2006
    Patterson La
    Where are you located? There might be someone close by that can help.

    cheeply: Off the top of my head
    SBT crank $400
    Pistons $200
    Gaskets $50
    Carb Kits $100

    You counterballancer is probably good. Your carbs will need to be rebuilt, or at least cleaned as well as your selector valve and screen on the baffle. 951s couldn't be any easier to build. The carbs aren't too tricky either. pull it out and strip it. You've got all winter and there is no better way to learn. I normally try to talk customers into an SBT rebuild on a 951 just because there is the chance that they will fill it with water or forget the oil, and then blame me for the failure. I'd rather loose out on a little labor money for the piece of mind of them having the warranty. I rebuild all of my engines myself. Get the manual and search this site.

    Besides, There is nothing better than cranking up a motor you built for the first time. (when it doesn't lock up after a couple of revs)

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