I should have clearly stated that blow-by would first show up and be most evident on the piston. The cylinder could have some glazing on the lower cylinder walls and which could have occured sometime ago (pre-current piston install).GS wrote:IC,
In the spirit of enlightenment, what does blow-by look like in your experience? Reason I ask is that Ive seen similar "brownish" coloring on seriously worn cylinder walls and I may have mistakenly credited it to just that.
After taking a fresh look, it does appear to have the "look" of light corrosion.
Cylinder glazing, if sever enough, can prevent the rings from sealing to the cylinder wall and which doesn't allow a good seal and set the piston up blowby. However this piston doesn't show any evidence of serious blowby (unless it has been cleaned off which I'm assuming it has not.)
I've never seen a case where piston blow-by shows up first on the cylinder or prior to the piston on a 2-cycle engine. Piston just runs too hot compared to the cylinder, so the oils get cooked onto it first when the rings are not transfering the heat and allowing fuel mixture to past.
When I looked at the cylinder in the picture I thought most of the dark coloring was due to the lighting coming through the ports and shadowing within the cylinder. I certainly could be wrong!!
It really does appear to me the engine got moisture into it somehow and was not throughly dryed prior to be parked for awhile. That is my best guess
