I am rebuilding a 2006 FXHO Cruiser, which had no compression on 2 cylinders. I noticed some water in the oil, and when I took the head off, found this gummy substance on 2 of the pistons. Any thoughts on what it could be, and what would have caused it? Should be easy enough to repair, but I am curious as to what happened. Would a bad head gasket do this?

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