After about 10 hours this is what my Pilot piston looks like. Going to run race gas and see if problem goes away. Never had this problem before. This is Pilot that I thought had low compression but ended up being a bad stator. All four sides look the same

That piston is more than useable.
Buff it up with a flapper wheel and file out the ring grooves with the wife's nail file. Rings look ok to me. Re-install it -- good to go. Then run Avgas (oh god here it comes).

Edit: You did do a pre tear down leak down test right ?? (air leak). At this point I would not spend the money on a new piston because you are unsure what caused it and that piston is good. Just my opinion.

That piston does look like it got real hot to me.
I can't tell by that picture but if those are not scratch marks on the very top (because you may have been looking for a piston number) of that piston then I would say very early sign of detonation.
If those are scratch marks made by you then it could be something else like a lean out condition. Cracked intake ?? Lean main jet ?? Air leak ??
At the end of the day if you are running factory jetting and your Engine had no air leaks then I gota say POO FUEL for sure.

I am not joking when I say re-use that piston and rings.
Your Engine died because of ring lock.
And that is probably why you had low compression to begin with. Ring lock was already beginning.

Did you say that all 4 corners of the piston are scored the same?

If so it's called a 4 corner seizure. Generally caused by getting hard into the throttle before the piston and cylinder have come up to an even temperature. The piston's 4 corners expand too quickly causing them to rub on the cylinder and cause the scoring you see.

Other causes are.....

Too lean carb jetting (main jet), or too hot of a spark plug range.
Look at the eighth picture down in the link below. The picture is a mild case but you'll get the idea.

http://www.smellofdeath.com/lloydy/pist ... _guide.htm

Av gas is great don't get me wrong but it can also be a band aid covering up the original problem. Your other pilots run fine without it.... don't they?

Rand

Look familiar ??
You sir have a girl machine.

This is the pilot I tried replacing everything on from coil to carb to piston only to finally figure out it was the stator. Interesting you call it 4 corner seizure. Because it happened within 5 to 10 minutes of our ride. The person riding it is heavy and there is a steep hill to get to the dunes from my house. It seized once immediately then cooled and made it about a mile before seizing up solid. Once we got it towed back and it cooled it turned over but no compression.

The piston did get real hot. It was at the beginning of our ride. I saved the old piston. I think those scratch marks are from the shop confirming size.

Another possible cause is the thermostat may be stuck in the wide open position which will not allow the coolant to warm up quickly. This will cause a considerable temperature difference between the piston and cylinder because the cylinder does not have a chance to warm up.

Without a thermostat, my water cooled Ody was one of the most cold blooded vehicles I have ever owned. After letting it set and warm up at an idle for 3 or 4 minutes, I used to have to put around slowly for a couple hundred feet before I could even think about getting into the throttle.

Rand

Thanks for the advice. Will ride it and see how she does. Any suggestions for breaking it in?

Back in the day we had Yamaha Raptors and I installed a temp switch that activated a indicator light to know what they were warmed up. This may be over kill but I bought them new and planned on having them forever so we really babied them.

I find it interesting that everyone seems to "warm up" their Engine before they go.
My oddy's have homemade water cooled heads and cylinders. When my brother and I go for a ride we just drive them off the trailer and line up. Then we flip down the visor and nail it. Most of the time it is straight up from where we unload the machines. We don't seize our engines. Also does anyone every warm up their truck ?? We just jump in and go right ?? Anybody every seize an Engine in the truck ?? Anyone ever seize an Engine on their dirt bike when we were kids ?? We just nailed it right ??
In my opinion four corner seizure happens on boats. That's because they use the lake water for cooling.
I would run Avgas or race fuel in that machine if it was me. Just my opinion.

"In my opinion four corner seizure happens on boats. That's because they use the lake water for cooling."

Well that's you opinion and you're entitled to it. Four corner seizures don't only happening to boats. I also swing a wrench for my neighbor who has several 2 stroke water craft. I have rebuilt two of his engines and they run just fine..... once they are WARMED UP. Never had a four corner seizure on one of those.

"Also does anyone every warm up their truck??" Yes I warm up my truck. About 2 minutes every morning or until the idle reaches its lowest point. I also warm up my 66 air cooled VW.
"We just jump in and go right ??" No, some of us don't.

You don't seize your engines because you have your piston to cylinder clearance set a little on the loose side.

Rand

I have said this before and have to say it again.
Machines have a personality. They are as individual as people.
No two machines are the same. One has a little more "clearance", one has a slight air leak, one has a bit more compression, one has a gap on the reeds, etc etc. You can buy two chevy's off the car lot and one is a complete piece of poo and the other runs like a swiss watch. Why is that ?? Because they have a personality.
You have a girl machine -- run Avgas.
Amen.

I run my truck (deisel)buggy (I always back the buggy off the trailer to warm up so the Trans has some oil thrown around),jetski,boat ,tractor , lawnmower i even run my chainsaw a few minutes to cycle oil and warm up a little. Just a habit I've done my whole life. Don't know if it's necessary but it sure can't hurt anything.

I see all the posts regarding burning up pistons and I just don't get it. I run all my 2 strokes rich and have never had an issue. My jet ski is a 1050cc 3 cylinder 2stroke sure its a little fat on the bottom and in the mid but I know I'm safe. Don't get me wrong i love a smooth power curve and screaming top end but I know I'm dancing on the line of screaming across the water and seizing it up.
Couldn't a lot of this be avoided by mixing you're oil a little richer or jetting fatter?
I did have a fl250 as a kid but I am not qualified on anything pilot or odyssey , just an honest question.

When my brother blew his machine several times we were running real fat. In fact the plugs were black. The problem was detonation. We kept blowing holes in pistons.
http://www.klemmvintage.com/deto2.htm

Just come out and say it ......

Canadian Gas Sucks! lol

Where does your gas come from? Is it refined in Canada?

Rand

That is one quote of yours that I will not argue with.
There is no doubt in my mind that canuck gas it total poo. They even rip us off when they sell it to us. Right now and as of today it is $1.23 a liter or in other words $4.96 a USA gallon. I honestly believe that yankee fuel is different than ours but I can't prove it.
Yes I believe it is refined here in Alberta and here on the coast at a refinery in Vancouver (Burnaby).

They do produce different gas for different regions. As u go north here in the states the additives differ to cope with altitude.
This is something I read several years ago so take it for what it's worth but it may play a role.

Not getting notifications! Arghhhhhh. Should I do something to properly break in this new piston?

[quote="FloridaEdd"]I run my truck (deisel)buggy (I always back the buggy off the trailer to warm up so the Trans has some oil thrown around),jetski,boat ,tractor , lawnmower i even run my chainsaw a few minutes to cycle oil and warm up a little. Just a habit I've done my whole life. Don't know if it's necessary but it sure can't hurt anything.

I see all the posts regarding burning up pistons and I just don't get it. I run all my 2 strokes rich and have never had an issue. My jet ski is a 1050cc 3 cylinder 2stroke sure its a little fat on the bottom and in the mid but I know I'm safe. Don't get me wrong i love a smooth power curve and screaming top end but I know I'm dancing on the line of screaming across the water and seizing it up.
Couldn't a lot of this be avoided by mixing you're oil a little richer or jetting fatter?


More oil in the gas makes the mixture leaner and an Engine failure is all but guaranteed. Large jets will richen it up. Not saying this is the answer just want to avoid the mistake/belief that more oil in mixture equals richer setup.

Dave,

Step 1.) Heat cycle the Engine by running it three times at idle until it comes up to temperature, each time after running it, letting it cool down until it is stone cold. Approximately 10 minutes running time for each heat cycle.

Step 2.) After you have done the three heat cycles, go take the Pilot a leisurely cruise not going past 1/2 throttle and varying the throttle constantly. You want to stay off the beach by the water because the extreme moisture in the air will effect jetting and cause it to lean out a little. A nice little 15 minute cruise should do it.

Step 3.) After she cools down completely, take her out for another cruise for about 1/2 hour, again varying the throttle and staying away from the beach.

Step 4.) Let it completely cool down and then repeat step 3.

Step 5.) After the complete cool down from step 3 & 4, go for your normal ride!

Rand

Thank you I should have specified the two. More oil dose displace gas and make for a leaner mixture however personaly I jet to the oil ratio I would normally run.
Again I'm no expert I'm just saying what I do and Im more then happy to keep an open mind as I know very little when compared to most of you guys and I just may learn something.

Thanks Rand. Will do that today

Anytime!

Rand