Anyone know what could have caused this kind of damage to a newly rebuilt engine?

[DJMky]

Went ahead and pulled the head today on the RX 951 that I purchased from a friend of the family. The background on this ski is that the engine went bad and they paid a certain shop in PA to do a rebuild which was around $1800. Upon getting the ski back on the water a few hours later it dropped compression in one cylinder and they stuck it in the garage where it set for a year until I recently bought it.
After doing a compression check and getting 125 on the front (the piston with the black coating) and a 25 on the rear cylinder (the chipped and hammered looking piston) i pulled the head and took some pics.
I noticed the front piston had a stamp on the piston and the rear did not. looks like it was honed and maybe a larger piston used? The rear piston just looks like it has been beat to death.
Anyone have an idea as to what would cause this? I plan on buying a new engine because the ski is mint but I don't want to install it and then have the same thing happen to me.
Thank you guys!!!!

[Tiny]

Either a ignition timing issue or fuel delivery issue. Most likely since it is a RX then it has the original fuel lines that have slowed the fuel delivery down and then caused this issue. The only way to really know would be to take the cylinders off and have someone look at the pistons.

Most people will just throw in a rebuild but never fix the problem that caused it to go boom in the first place......

[Mr. GP1800]

Most people will just throw in a rebuild but never fix the problem that caused it to go boom in the first place......

This is why 2 strokes have a bad reputation among lots of people on this forum. The fuel systems have to be maintained perfectly, or failures like this happen. So many people just throw in a new motor without finding out the real cause of the issue. I am willing to bet you still have the grey tempo fuel lines in it. Upon going inside the carb for that cylinder, you will probable find clogging with green goo, caused by those fuel lines. Get the carbs cleaned and rebuilt, replace all fuel lines, repair the engine and I bet you will be good to go for a long time.

[wkuadam07]

The front one looks like water ingestion, probably from a bad exhaust install to me... but i don't see a lot of that, experts will chime in there. The other one looks like either the engine wasn't cleaned out properly and there was a piece of metal in it, or it ingested something metal, or ran extremely lean and broke the piston apart and caused the pitting.

Here is the deal, get a new (re-manufactured) engine for the ski and take all the proper precautions when it's installed. Proper precautions include a carb job done by someone who actually knows what they are doing unless it's a DI, all new gaskets installed properly, fuel lines replaced IF they are still grey, gas tank cleaning, fuel selector leak check, jet pump inspection and rebuild if necessary, and empty the oil tank and replace with the proper oil if you aren't dead sure what has been poured in there. 951 has to have seadoo FULL synthetic or the equivalent, Amsoil Interceptor is excellent, Quicksilver PWC synthetic is OK, oil intended for outboards will result in engine damage. The oil system must be bled out and adjusted properly as well. If it's a DI then get the injectors cleaned and tested, pull the fuel sending unit and replace the filter, check the fuel pressure upon re-assembly, cross your fingers, pray, knock on wood, and read many threads about what to do WHEN it doesn't run right...

If you cover all your bases during the motor swap you will be very happy, if you take the first shortcut you will be replacing the motor AGAIN... Somewhere while checking all this stuff, you should find what happened to this motor. Whatever happened to this one, happened to the original... find what killed them and your motor will last.

[DJMky]

Yes guys you are correct it does indeed have the grey tempo fuel lines. These are exactly the answers I was looking for. sounds like I should go ahead and have the carbs rebuilt, swap out the fuel lines and then add the new engine. Anyone recommend someone who does carbs?
Thanks again!

[Mr. GP1800]

Where are you located?

[DJMky]

Northern Kentucky.

[wkuadam07]

I don't make it back home very often, but I'm from Dry Ridge... Ever make it to Bowling Green? That's where i am now...

[Myself]

Yep, fix the failure but not the cause. Typical of a lot of shops I'm afraid. Not to mention possibly some remaining debris in the ports bouncing around that was not cleaned up the first time. Looks like a lean burn down to me.