Originally Posted by Yellow Pig
Looks kind of like the valve seals to me. Now if it is the valve seals I'm I better off going a head and doing the wossner piston kit w/ the better oil rings and be done with it or just reuse the OEM piston and rings?
You've already got it apart. Wouldn't it suck to put it back together and still burn a crapload of oil? I would go ahead and replace the piston just to improve my chances of avoiding another teardown.
Besides, valve stem seals shouldn't affect your leak-down numbers, so the pressure is either getting by the valves themselves or the rings. The rings on the stock piston are known to be problematic.
I should point out that my previous comment, "especially at 100 hours" was not meant to imply that 100 hours is a lot. If you had said 200 hours, I probably would have said not to bother with the leak-down test, just go ahead and replace the piston if it's coming apart anyway.