If you’re talking about the carbon flaking off the piston I’ve never seen that. Most of my saws have carbon on the top but none that would likely ever come off.
The piston and rings look pristine. The cylinder looks pristine. The carbon on top of the piston looks thick enough to increase compression, maybe even hit the squish band, and it is flaking on top of that. It looks odd to me.
The flaking in chunks is what’s odd to me. My saws are old and certainly have that much carbon but it’s hard. Not sure why his is coming loose. That part is over my heas
Since the rebuild, this saw wasn’t run too much until May of this year and then ran hard all summer long. As of lately, it’s been my backup to my 462 because it had some AV issues I knew about and needed to address but wasn’t ready yet, until it made me ready on its own last week. So it really hasn’t seen any real cold temps yet, but it was run on 95-100F degree days..Maybe it is from a really hot piston and really cool cylinder from running hard in the middle of winter?
The weird part IMO is that there is no sign of any damage, either to the piston, cylinder, or combustion chamber. But when I pulled the piston, it was literally flaking off..
Great perspective! I think they call that “survivorship bias”.
I’d say that carbon came way before switching to that oil? Maybe it’s cleaning it off? Is that a good thing? Could a chunk lodge heading out the exhaust ?
I think you are seeing the piston wash from the incoming intake charge. Where the piston top is shiny, it didn’t flake there at all.
346 failed ported
Very hard, crusty. If you wipe your finger across the piston top you get very fine particles on your finger that looks like when you handle charcoal.
