Gp1200r Millenium third piston shot, welded lower ring, troubleshooters welcome

[TuckrD]

Hello, I have a 2001 GP1200r that has a third piston shot.

I was at the lake over the 4th and took my Jetski to the water. Ran it for about a minute and it shut off. Was at 45 on the dream-o-meter when it cut out. Tried starting it, but electronics weren't responding and the engine sounded labored. Took about five tries to get it started. Brought to shore and ran a compression test. The third hole was reading 30 or more psi lower the #1 and 2.
When I got back, took the third jug off to find this. I am unclear what made the scour marks, gather something like sand fed through. The jug itself is real actively smooth in the respective locations.

This is the intake side,


This one is the exhaust side, looks like the lower ring got essentially welded to the piston.

[TuckrD]

The ski is D-Plate, premix, jetted, free flow exhaust, flapper removed, jetworks moded.

[Mr. GP1800]

Had the carbs been checked/cleaned/rebuilt recently?

Have any more pics? A not so close up shot of the piston including the piston top? Pics of the cylinder?

Any chance the motor was sucking water?

[Robfromga]

What does the wash look like? Plug? Rod play? Looks lean seized

[mikegp]

check the rear crank seals for any sign of oil leak .

[Mr. GP1800]

Its really hard to say without seeing more.

[TuckrD]

Had the carbs been checked/cleaned/rebuilt recently?

Have any more pics? A not so close up shot of the piston including the piston top? Pics of the cylinder?

Any chance the motor was sucking water?

Carbs were just rebuilt about two months ago, and it didn't need it, no oil in the hull. Engine had sucked up water, and was letting it pass through. May have not let all evacuate before going for it. Just ran finger on rear seal, nothing abnormal, play on shaft is nothing out of normal.
Also, fuel selector removed.

[Robfromga]

http://www.snowest.com/forum/attachm...1&d=1228760998

Your not horrible lean, but its lean. Also the piston being shot and not sealing screws up the wash. So it probably was OK.

[Robfromga]

Your not missing the power valve screw are you?

[TuckrD]

Your not missing the power valve screw are you?

Nah, just a great angled shot to make it seem that way. As far as it being lean, it is plausible. We were in the midst of dialing the setup in. got the lows, but a little left on the high side. Plugs looked normal.