the second picture is a different bore and when i built the engine up i stored it in the conservatory until i was able to fit it that was about 2 months

thanks guys starting to feel a bit better

The second one is a fairly clear horizontal line, looks like water lying on a ring and corroding. The first picture could be droplets of condensation. If the engine was put together in a hot, damp environment and then stored in a cool place could account for it.

As I said earlier, I doubt these small bore imperfections would cause significant symptoms in their own right, however they do indicate a presence of water lying on a ring which could then stick in the piston.

The next step IMO is to lift the pistons out to look for further clues. If rings are stuck, then you've found the culprit straight away. If not, look for signs of blow-by on the pistons. These are dark patches which drop down from the rings and will indicate where the hot combustion gasses are escaping past the rings.

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