Damaged Pistons (pictures)

[Babylissa17]

Hi there,
I’m new here and I was reading some forums in damaged pistons and was wondering if I can get you guys to look at them with the pictures provided to let me know how this might of happened?

Also if I rebuilt it what are my chances this will happen again?

I currently have a 97 XP seadoo,

 

[JeremyD615]

It appears that you’ve got a cylinder that was fuel starved and ran lean... If you rebuild it without addressing the fuel system issue it’s very likely that it will happen again. Pull your carbs apart and see if there’s an obvious obstruction or issue with the one on the bad cylinder...

 

[benjilafouine]

When my engine was damaged (it was gone) in 2015, I had the mechanics change as well the fuel pump, weld the muffler and I even threw a new carb in for good measure. You're in for a big job. But the reward is that four years later, my ski still runs perfectly.

 

[mikidymac]

That’s classic preignition aka detonation, you can see how the middle of the piston crown is eroded away.

Typically from old fuel that has lost its octane or too thin of a base gasket on the cylinder making the squish too tight. Mix thoroughly with a dirty fuel system and/or carbs and there you go.

If it was just running lean it would seize but you wouldn’t have the eroded piston tops.