ORIGINAL: PreyForTomorrow

So i took off the back plate and looked inside today to check for rust. I can't really tell what i've found. Everything inside looks clean except for (what i think is) the crank shaft. It's kind of hard to tell from the pictures what everything looks like so I posted a few in case one helps more than the other. To get your bearing, the bottom of the engine is to the left on the pictures and the cooling head is off to the right. When I wipe my finger on the brown part, no rusty residue comes off, only oil. Is it normal for this piece to be brown but everything else clean? I kind of looks like the burned top of a piston, only this is all over.