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  1. #1

    Is it time for a new engine? Kawa sts 750

    Quick question, I think. I am riding my kawa sts 750, a 1995 model, at about 3/4 throttle, and all of a sudden it just slams to a stop, no wind down or clatter, just slams instantly to a stop. Was running great on an sbt rebuilt engine about a year old, at least as I am told since I have not had the ski long.
    Shore inspection showed that the front piston had slapped the spark plug, closed the gap on the plug and actually knocked the plug a little loose in the hole?
    Engine is seized. Is it automatically time for a new engine, or is some further tear Down and inspection needed? I see some metal bits on top of the piston, but no hole. Your thoughts are appreciated.


  2. #2
    Well that seems to be pretty catastrophic damage. People use sbt because of the cost (and their great warranty). You have probably bent a rod, so the crank is toast, and crank+new pistons, gaskets, boring/hone, possibly head + misc stuff and labor, it is just cheaper to go the SBT route. With that said I would still tear the thing down and find out what happened.... My first guess would be water ingestion, is it premix or oil injected? sometimes a oil line will crack or fall off and one of the cylinders will lose its lubrication and seize hard, that is a possibility as well....

    If you take it apart and take some great pics some of the experts here will give you a diagnosis and then you can decide what to do.....

  3. #3
    you it is also possible that the plug was loose to begin with, let a little air in causing you to run lean and you burnt up a piston???? That happened to me on a skidoo once. My brother had been working on it and didnt have the plug torqued down, i didnt know, 10 minutes later I was walking home... Now I always check my plugs before I go out....

  4. #4
    steve45's Avatar
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    The first thing to do, since it's an SBT rebuild, is to check with them to see if it's still under warranty.

  5. #5
    Yep, out of warranty by about six months. Plug was not loose, i have now torn down the engine, I hope the pics make it through. This ski is new to me, I am suspecting something bad happened to it before I got it. Was running well, although sometimes it would not take off, and had to be choked a bit before taking off, and would then run well, for about three hours before it blew. thats probably a pretty good hint.
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  6. #6
    Sorry the pics are lousy..I was pushing the limits of an iphone. One pic shows the bad piston, the top half looks pretty good, the bottom half of the same piston exploded and found its way into the reed cage. The rod is broken under the wrist pin. The other piston shows significant and wide spread scoring, causing me to think something bad happened to the engine. The internals were oily, by the way.

  7. #7
    steve45's Avatar
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    Yuck!

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