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  1. #1

    Piston Seizure - What Should I expect?

    I'm looking for guidance on what may have caused my piston to seize on my 2002 XLT1200 and what I can expect rebuild wise, just an easy top end or will I be looking at a complete bottom and top rebuild.

    Here's my story... I purchased this jetski from a pwc mechanic 2.5 years ago. He rebuilt the topend and carbs for a customer who ended up short on cash. He took it over on a mechanics lien and then I purchased. The first time out, the buzzer went off within 15 minutes. He stated air was mixing with the piston causing it to heat up. He gave me a 30 day verbal warranty when I bought it and he fulfilled the promise. He tore it down and put in a new hot rods crank and rebuilt the top end again at no cost to me. The cat was removed years ago and when I purchased it, he removed the oil injector. From day one I only used non ethanol gas and a 40 to 1 mix of Yamalube 2stoke oil.

    My second time out with the new rebuild 2 summers ago, I forgot to put in the plugs and long story short, I couldn't crank it at the beach. A storm was rolling in so a guy helped pull it back. During the process, the jetski turned sideways and as I found out later that afternoon, all of the water in ski rotated into the engine. This was saltwater. That evening I was able to get the water out and start the ski. I ran it for a long time and then the next morning rode it for hours to get all water out. After this incident, we had 2 solid summers of use without any issues, she ran great and I always flushed with fresh water.

    This winter I had my guy winterize and fog the motor, first time since I owned it. When I took it out for the first time this season, she started up and ran great for 30 minutes at all rpm ranges. After coming to a drift to go under a bridge, I gunned it and as I was coming up on plane, I lost about 70% of power immediately. I'm not a smart man. I kept giving it throttle to limp over to the docks. Once at the docks, it completely locked up on me. I took it to my guy and after taking the piston cover off, we saw metallic rock like chunks and powder on one of the pistons. His thoughts were that I needed all new pistions & rings, a new jug for that cylinder and I may need to rebuild the bottom end of the ski. He suggested that something from the bottom could have gotten on top of the pistion and was pulverized. I may have misunderstood him as he knows his stuff, but it looks to me that the piston overheated and started to breakdown, the pebble like material came from the piston breakdown material being compressed and not from the lower end.

    My main question other than what may have caused this issue, is what's the likelihood I'll need to replace the crank. What kind of money am I looking at to repair this ski excluding labor costs. Also the exhaust is a pain, are there any youtube videos with a walkthrough? If it's a complete bottom and top rebuild, what are your thoughts about aClick image for larger version. 

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ID:	335577 SBT replacement? Attached are a few pictures. Thanks for your time reading this novel and your response!

  2. #2
    Lake Lion
    Join Date
    Jul 2007
    Dirty Jerzey
    Looks lean to me. There is no wash on the other pistons. The experts will chime in soon.

  3. #3
    RaiderMagic's Avatar
    Join Date
    Aug 2013
    South Shore, Long Island NY
    outers look lean. rocks are your crunched up piston. Are you still oil injected? how the lines? any oil in the hull? Kinked or loose lines? How many hours on ski/oil pump?

  4. #4

    Join Date
    Sep 2013
    Bennettsville, SC
    Looks lean on both outside cylinders. Those pebbles are pieces of aluminum. You may get lucky and not need a crank. Definitely check your carbs with a fine tooth comb. I'd bet dollars to donuts they're dirty.

  5. +1 by:

  6. #5

    Join Date
    Aug 2006
    I absolutely would not use that crank. Why take a chance when all that debris was down there grinding around before it quit running. Then you have to figure out what happened, dirty carb, air leak, ect.

  7. #6
    Click image for larger version. 

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    I took off the exhaust manifold and chunks of the piston skirt and wristpin pins fell out. It's a complete rebuild, reman or purchase a used motor that I'll start next spring. I premixed from day one, oil injector was removed. I used a 40 to 1 ratio with Yamalube 2 stroke oil. The catalytic converter was removed previously with a D plate added. Are there different jetting options for these carbs like a dirtbike, or does everyone just use the same jets and needles? Just curious if it was jetted incorrectly or if the carbs were dirty. If it was an airleak, would this be taken care of with a new reman motor and rebuilt carbs? When I originally purchased the ski and the buzzer came on during the first ride, the mechanic said it was an air leak on one of the pistons. Could there be an issue with the case itself assuming this second failure was from an air leak? Thanks for your help.

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