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  1. #1

    Read My Piston Damage!

    Here is a pic of my OTO pistin. The arrow on the left points to a 3/8 piece of the top ring that is melted to the piston. The right arrow is the locating pin that is no longer there. The side of the ring appears (to me) to reflecct the scaring of the pin as it was drug up and down the piston side. Amazingly, the cylinder wall has an ever so slight mark that will be removed by a minor honing.

    From what I have read on the forums, the top of the piston looks like it was way to lean! The other two pistons were completely covered with dark soot, but fine otherwise. There were no signs of any piston wash on any piston!Click image for larger version. 

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    I am currently rebuilding the entire engine. '93 SL650. Am I correct in my read of the piston?

  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
    Join Date
    Oct 2006
    Cleveland OH
    It doesn't appear to me to be a melted ring. But could it possibly be the actual locating pin?

  3. #3

    Join Date
    Aug 2006
    Homer Glen Il.
    I ave a 785 piston just like that and really never thought about what had happened to it Very weird , time to see what Jay or Randy think

  4. #4
    Join Date
    Mar 2009
    Bronx, NY
    O had this happen on a seadoo 951 motor. The set pin fell out and the ring eventually tagged a port. Surprisingly I got away with a hone.

  5. #5

    better Picture

    Here is a better/closer picture of the ring etc. I hope I did it right..can't see the pic right now!
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  6. #6
    casey67's Avatar
    Join Date
    Sep 2006
    It looks like the upper ring pin is at the end of that ring. Where the top arrow (peice of ring) is pointing.

  7. #7

    casey67 is right - my mistake

    I pryed the broken ring out and I was wrong. The upper pin is at the left side of the broken ring. Not sure what caused the gouge in the piston. Possibly just crud from the top of the piston? The reed cage from that piston (the metal reed stops) have the same crud on them. All the reeds, however, are in perfect shape and are the originals?

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