95 XP Piston Damage

[scarter64]

Just rebuilt Seadoo 95 XP 800 motor. During the initial test in the backyard we burnt the piston toward the front of the jetski(mag. side). Back piston also showed signs of heat damage but not near as severe as front piston. Used premix gas approximately 32:1 for break in. Engine was only run maybe 30 minutes. All cooling systems seem to have been working properly. Anyone have any ideas what maybe causing damage?

Thanks
Stan

[96XPSS]

Hey Stan.,..welcome!

Exactly what is your definition of "rebuild?"
Top end?
Whole engine?
Were the carbs disassembled and cleaned?
Did you run it in the water wot?
Who clearanced the pistons, and where were they measured from?

A pic is worth a thousand words...if you can shoot us a pic of the sides of the burnt piston we can tell by the damage what caused it.

[scarter64]

Thanks for getting back with me. The ski is a 97 XP not 95 XP. Sorry brain fart on that info.
We put a new crank assembly, new pistons, everything new. We rebuilt the carbs last year and seem to work fine until motor went last summer. We also went through the carbs again to make sure we had no trash. We had a local engine builder to look at the cyclinders and they were suppose to be okay. Honed cyclinders but replaced everything stock top end and lower end. In taking the pictures we notice that instead of heat damage it looked like a piece chipped off the top of the piston. Sure enough looks like the rave valve made contact with the piston. We also looked at the old pistons we replaced and they showed no sign of damage from rave valves. The rave valve is damaged from where it looks like they made contact. Have you ever seen or heard of this. Looked at rave valves during the rebuild and the looked okay. Is there some oversight on our part. Please give me any feedback and recommendations you can.
Thanks
Stan

[RX951]

Welcome to the forum stan

[water worx]

What size did you bore it to ??

The raves need to be cut at .050 or over.

[scarter64]

Did not bore the motor, went back with everything original.
Thanks
Stan