It also looks like you are loading that engine too hard. The crank and bearings show signs of heat.
This style engine does not have any extra area to soak away heat due to the case not being mounted to anything else that can sink the heat away (usually the cast metal oil tank) If anything the plastic that the engine assembly mounts in insulates and holds the heat.
I imagine you must have noticed while running it hard like that that it would lose power sometimes and if stalled was hard to restart until it cooled down.
This style saw is not a great choice for dirty cutting conditions which dull a chain quickly which I imagine is what you use it for.
The price difference can make using the semi pro saws worth using and run till they blow though.
I did used to run the saw very hard. And all my cutting is normally dirty. However for £35.00 and 6-months use However the education in stripping it down and now started to re-build invaluable.
I think though you may have hit the nail on the head. Was asking too much of the little darling.