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Can’t tell from all the dust.
I know bad pictures he sending. I'm gonna have to wait till Tuesday but with what I have at least he is kind of locked into its condition before he decides to squeeze some 2 stroke in there lolCan’t tell from all the dust.
Straight gassing does not typically toast the exhaust side of the piston...that is a lean condition.
Scoring comes from a couple things. Heat or mechanical failure... broken ring, bearings, carbon etc.
Can we agree that straight gassing causes the saw to run really hot (friction)? And the exhaust side of the piston is exposed to the highest temps?
So how does straight gassing not toast the exhaust side of the piston??? Every straight gassed saw I've ever seen has damaged the exhaust side. If caught early you are dealing with aluminum transfer, or in other cases a piston that tries to weld to the cylinder walls.
The lean condition you are referring to is an air leak I assume? Which simply means the saw isn't getting enough fuel/oil to lubricate properly.... again causing HEAT and the exact same symptoms.
In my experience, when only or mainly the exhaust side of the piston is melted and leaves transfer on the cylinder, that is cause by a lean condition, usually an air leak. Yes, the exhaust side of the piston is the hottest. I the case of a lean condition burn down, it's the extreme combustion and exhaust heat that starts to melt the exhaust side until the ring land smears and "seizes" the ring resulting in the loss of compression and the engine to stop running but not locked up tight most of the time. Most times the intake skirt is mostly unscathed or sustains little damage compared to the exhaust side...again based on what I have put my hands on. I have seen extreme cases of a lean burn down on larger two-strokes where the exhaust side of the piston crown had actually begun to erode away leaving a rough/pitted finish.
The piston showed by the op had definite scoring to the intake side of the skirt, and alot of it. Most likely from bearing debris flying around in the bottom end.
Now talking about straight gassed, we all know that piston skirts expand when they come up to temp, but still not to zero or near zero clearance with the bore. You can easily start your saw that is still hot two seconds after shutting it down right? Yes, mix oil does play a role in piston/bore lube, but I see the ring/s amd bore as a little more durable to no oil supply than the bottom end bearings. There is an inherent slippery relationship between the rings and plated bore. But based on what I have seen, the bottom end is usually the first place failure occurs in the absence of mix oil. Bearings spinning at 10K or more rpm will exhaust their oil in pretty short order when the oil supply is cut off, especially the caged needle bearing that is the lower rod bearing in this case. It's the weakest link in the system. It takes the up and down stress of the piston stroke as well as rotational load. That bearing works hard. Now add the factor of heat already present in the bottom end of a saw that is fully up to temp and running hard.
I still say: Straight gassed/extremely poor fuel quality, lower rod bearing failure.
Lets see what the OP comes back with.
You sold an XPW with Meteor cylinder for $650?? Dang!!!Well hopefully he sends me more pictures, but I can't help feeling bad for the guy. I sold it for $650 (a beautiful 372xpw 32" b/c) I went over this saw so thoroughly before he took it. There is NO way he didn't put gas in it before he used it. Any person would of checked and topped off the bar oil and gas before firing it up. Right???? But I do know that based on how he responded to my question about fuel mixture he said he didn't fuel it and was only using the gas I had in it when I gave it to him is total BS. I didn't have a lot of gas in it and no way near as much needed for 20 minutes of use at WOT. It's like the people I used to stop for DWI....they ALWAYS said they only had two beers/drinks when asked what they drank. Lol
But I can't help feeling I missed something? But I didn't. If I kept this saw I'd be screaming her through rounds of wood without any issue. I know that, but now I have to defend my sale, that what makes me not want to do this anymore.
I didn't even look. That's a meteor.piston on there??You sold an XPW with Meteor cylinder for $650?? Dang!!!
Don’t know about the piston, but that’s a Meteor cylinder.I didn't even look. That's a meteor.piston on there??
YepDon’t know about the piston, but that’s a Meteor cylinder.
I’d be pissed
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