When I drained the oil from the oil pan on my 400ex, there were metal shavings in the oil. I pulled off the right side crank case cover to get to the oil screen by the pump, and that had shaving in it as well. I got a magnet, and some of the shards stuck, but some didn’t. I’ve already got the top end torn down for a rebuild, and there doesn’t appear to be any damage to the piston or cylinder wall.
I know it was bored out to 416 by the guy I bought it from, but I don’t know how many oil changes have been done after that was done (this is the first time I’ve changed it). Could the metal I’m seeing be left from the break-in of the rebuild, or should I be looking somewhere else?