Weird piston action in a blown Stihl 500i

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Dealer has never seen a piston do this. They sent this vid to the district mucky muck but no word as yet. Anyone ever seen this?
year old tree service saw. Always run with the new, recommended Stihl mix oil at 50:1.
I’m waiting to see if Stihl will do anything, warranty wise…doubtful…before tearing it down.
 

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Is that with the spark plug in or out? If the plug is out then there's probably debris in the bearings or perhaps the crankcase and it's jamming things up.

I'd expect a dealer to have removed the plug to turn the engine over but they might have been in a hurry.
I called her :p. That vid was with plug in. She pulled the spark plug and tried it again…no change, still does the bounce.
 
Dealer has never seen a piston do this. They sent this vid to the district mucky muck but no word as yet. Anyone ever seen this?
year old tree service saw. Always run with the new, recommended Stihl mix oil at 50:1.
I’m waiting to see if Stihl will do anything, warranty wise…doubtful…before tearing it down.

BTW, I see them every day. It's called straight gassed. Nothing special about it.
 
You can’t tell if it was straight gassed without looking at the intake skirt. Straight gas scores all the way around.

I’ve seen several 500’s do that. The fuel values get scattered and it can’t recover. Needs reset with the MDG software after the scored parts are fixed.
 
Dealer has never seen a piston do this. They sent this vid to the district mucky muck but no word as yet. Anyone ever seen this?
year old tree service saw. Always run with the new, recommended Stihl mix oil at 50:1.
I’m waiting to see if Stihl will do anything, warranty wise…doubtful…before tearing it down.
Try rocking the flywheel back n forth. (Free play). Possibly rod bearing gone
 
You can’t tell if it was straight gassed without looking at the intake skirt. Straight gas scores all the way around.

I’ve seen several 500’s do that. The fuel values get scattered and it can’t recover. Needs reset with the MDG software after the scored parts are fixed.
Did Stihl help at all with the ones you repaired? Maybe a percentage on parts, anything? This is a tree service saw, 15 months since it was bought, new. I certainly wouldn’t expect full warranty but if this is a glitch known to them they might at least cover something.
 
Depends on the dealer and customer, how good of a dealer and how good of a customer. I’ve heard of them fixing stuff just outside the warranty and I’ve seen them blame it on straight gas at 3 months old.

I’d just clean up the cylinder and put a $100 oem piston in it. And have the dealer recalibrate it
 

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