What do you think about these pistons?

[mikidymac]

I finally got my 1996 XP engine apart and all looks good but there was a little surface rust in the cylinders from sitting for 5 years but the crank looks great. I didn't want to spend much but the pistons have a few little lines on them. These are the factory first bore pistons and you can still see the crosshatch on the cylinders so I don't think this ski had many hours.

Please take a look and let me know if you think I should reuse these pistons or get new ones. Either way I will be replacing rings and hit the cylinders with a ball hone. The piston pins were a little harder to remove than I would have liked too. Just looking for a second, third or fourth opinion.

The MAG is or right and PTO on left. Thanks.

 

[SabrToothSqrl]

Why take the risk? You really want to do this twice?

 

[donkey]

ive only built 2 seadoo engines thus far,but,i build hi hp hi rpm 2 stroke and 4stroke engines for desert racing all the time.i would not use pistons with those marks in anything i build,whether it be one of our race bikes or a customers'.
just my 2cents.
also,,using a ball hone can "hide"problems in a bore because the balls will "follow" irregularities,instead of pointing them out ,like a flat hone.
troy

 

[Dr Honda]

They look good... but since they are out... I would probably just put in 2 new ones.

 

[mikidymac]

They look good... but since they are out... I would probably just put in 2 new ones.

I was leaning towards replacing them but if everyone said to use them I probably would. The stiff piston pins had me more concerned than the marks I just didn't want to spend another $250.

 

[68ragtop]

The marks look to be at the locating pins. Wondering if the rings had a sharp edges at the gap, or just carbon built up from the ring gap. Guessing the same marks are on the cylinders & maybe transfered to the pistons?

 

[mikidymac]

Cylinders look good but they were running Wal-Mart oil and the rings did have carbon sludge on them so could be.

 

[get_real]

I wouldn't risk it, since you have them out and are saving labor doing it yourself why not just get new ones with new pins. Unless your just trying to get it back together to sell and maximize your profit, I'd replace.

 

[racerxxx]

The pins on the rotax are always a nice firm press fit with OEM pistons. Whether liquid cooled or Fanners(fan cooled sleds) you need to tap them out with a socket and use some good steady pressure to press them back in. I wouldn't be concerned about that, if they slipped right in or out I'd worry. I'd almost be willing to bet that your score marks came from a slight bit of rust on the edge of a transfer port while you were pulling the jugs off. Those scratches look too clean to have been run like that. I'd hit the score marks with some 800 wet paper, clean the crowns, re-ring them, new OEM wristpin bearings, hit the bores with the dingleberry hone and put her back together. Those score marks don't even look like you could catch a finger nail on them.

If your not using them and are gonna trash them, send them my way, I'll use them in a project.

Check the marks verses the transfer port, they look really darn close to where your marks are. (random ebay pic)

Also, since the pins are a press fit Bombardier uses a pin puller, It's in every seadoo manual. This is just an example of one.

 

[mikidymac]

Thanks Racer, You can feel a little bit with your finger nail and I have seen and used many worse. I think you are on to something with the rust. Like I said in the first post there was some surface rust on the cylinder walls and you could see a little pitting on the rings. The skis were sitting for 5 years and when I got them they turned over by hand and I put a little 2 stroke oil in just to make sure they were not dry when I checked compression and tried to start them. I only ran it a few seconds to make sure the electrical was good and they were candidates for restoration. I am sure the surface rust and short run could have caused this. My cylinders look better than the one you posted. Normally I would slap them back in and not think about it but I am starting to think I might keep this one. Since you and the good Dr. think they look fine I will probably just clean them up and reuse them for a few more seasons. I will be ordering new rings. I maight see how they clean up with some 800 grit before I place my order though. I will post some pictures and see what you think after they are clean.

I have used the pin puller at a shop but never owned one I could use at home so I just use the socket method. On this one I cut a 14mm socket into pieces so when I drive it through it acts as a short piston pin and holds the needle bearings and thrust washers for the pin pearings and they can be reused and do not drop into the cases.