Metal through an 865

[shawn_NJ]

I went to proactively replace my wrist pin bearings to the seadoo cageless ones, and after taking the head off find this. Looks like some very small piece of metal made its way though my rear cylinder. Wrist pin bearings were perfect, no wear. Crank/bearings look fine. No damage to the bottomend at all. Running single screen on the stock intake. You can see a very very small gouge on the side of the piston where the metal "passed by" to the top. Planning on a 100% complete rebuild after daytona this year. The piston and dome cleaned up pretty nicely by wetsanding the rough spots. Debating to gamble and reassemble/run it as is till end of this season, or do a whole new top end now... Ski was still running like a champ prior to disassembly. Thoughts?

 

[jamesgunter68]

what compression are you running?
any pics of the domes?

 

[motoman96]

Guessing you cleaned piston tops before pic? If not I'd be worried.
See signs of detonation tho on the right side.

 

[jamesgunter68]

Guessing you cleaned piston tops before pic? If not I'd be worried.
See signs of detonation tho on the right side.

^^^
thats what I'm thinking
check timing to make sure that you're not too far advanced
and make sure that your running the right octane for your compression

 

[shawn_NJ]

Guessing you cleaned piston tops before pic? If not I'd be worried.
See signs of detonation tho on the right side.

No we did not clean anything up before the pics. I was thinking it was deto as well, but you can clearly follow the path of the piece of metal from the transfer port, to the side of piston/cylinder and then the top. Looking at the damage under magnifying len really shows it looks like the result of physical impact.

 

[shawn_NJ]

what compression are you running?
any pics of the domes?

Never checked the compression. Pump gas domes setup by XS. EPIC curve setup by XS. Will get pic of domes tom.

 

[motoman96]

How much time on this motor? You have ZERO carbon which brings up some suspicion. Blown o-rings plus deto.

 

[shawn_NJ]

How much time on this motor? You have ZERO carbon which brings up some suspicion. Blown o-rings plus deto.

100hrs+ Ski ran phenom in daytona for 6days of riding. That was the last time I rode it.

 

[motoman96]

Def blown o-ring which washed all the carbon off. Doesn't explain the deto, but zero carbon on pistons is a dead giveaway of water intrusion.

 

[snowxr]

Must be running very rich to have no carbon buildup or wash after 100hrs.??

 

[shawn_NJ]

Must be running very rich to have no carbon buildup or wash after 100hrs.??

It does run pretty rich just based on fuel consumption. I have ridden many other 865s and mine seemed on par with the power delivery, so I never messed with the carbs.

 

[Crab]

Way rich IMO, prolly leaving a bunch on the table...

 

[BruceSki]

Did you check the cases to see if a small bit of epoxy broke loose and made its way up the transfer? Then maybe blew right out the exhaust or burned up?

My one good piston looked the same as yours. It is probably due to a rich setting on the carbs. I'm no jetting expert but I know xscream likes to run large needle and seats with large low speed jets and low popoff pressure which = a lot of fuel.

I'd send pictures and ask if that's what their motors usually look like torn down at that amount of hours if you have any doubts.

 

[shawn_NJ]

Did you check the cases to see if a small bit of epoxy broke loose and made its way up the transfer? Then maybe blew right out the exhaust or burned up?

My one good piston looked the same as yours. It is probably due to a rich setting on the carbs. I'm no jetting expert but I know xscream likes to run large needle and seats with large low speed jets which = a lot of fuel.

I'd send pictures and ask if that's what their motors usually look like torn down at that amount of hours if you have any doubts.

Ya I saw from your pics that your piston wash (or lack there of) was just like mine. My XS771 also was the same. We looked at the epoxy as close as you can without breaking the bottom open. Nothing obvious. Reeds also all looked 100%. I plan on talking to XS on Monday for sure.

 

[jamesgunter68]

I would say blown o ring since there is no carbon on the piston but I would check compression when you get it back together just to be safe

 

[BruceSki]

For all the blown oring sayers!
Here's how my one good piston looked. The other had a run in with pieces of wrist pin bearing so it looked a bit more gray. I had little to no piston wash either.

 

[BruceSki]

That was with no blown orings. They were all intact with 1 season on the motor. Never had any running issues related to water in the motor from a bad oring.

 

[Breese08SJ]

Def blown o-ring which washed all the carbon off. Doesn't explain the deto, but zero carbon on pistons is a dead giveaway of water intrusion.

Just to confirm there are definitely no blown o rings on this motor. Shawn and I tore this motor down together at my place today. Not the slightest sign of water intrusion in the cylinder. No milky oil/water slop in the cylinder, none in the bottom of the cases, not even hint of light surface rust on either sleeve at any point in its life.

 

[Breese08SJ]

 

[Breese08SJ]