I own two 2001 Waverunners and one of them over the weekend blew the motor. I thought the motor was toast but as it turns out it was just a blown piston. Here is the result of doing 50 and then only moving about 15 miles an hour.
Here is the actual broken piston (sorry couldnt figure out how to get the camera to focus):
Here is the good pistion next to it and you can see how much of that piston the engine just ate up and spit out...
And here are some more pics.
Well, $700.00 in parts later and the ski is running like new.