Exactly. A couple of things come to mind, a really rich condition which points to an EFI issue, a PAIR system malfunction where it was pulling crankcase gases without closing the valve, and possibly a rider issue if it was lugged for a long time. But what it isn't, is a fuel quality issue. You are right about the quality of gasoline sold in NA. Even if it's not Top Tier gas, the level of detergent mandated by the Fed's is more than adequate. Would have liked to get a nose on the oil. Really rich should show up in the pan and maybe the cylinder walls. A PAIR system issue should show up in the intake runners and clear back to the valve cover. The gunk in the cylinders looks suspiciously like the gunk that covers the reeds in the valve cover. But, I'm speculating without the motor on my bench. I just know it isn't fuel quality.