What does this indicate?

[JKLNHYDE]

So I managed to have time to run 4 tanks of fuel through my truck today and came home to do my usual maintenance routine an decided to check the head screws and found one to be a little loose. So I took them all out to clean the cooling fins and decided to look at the piston and saw this. It looks pretty burnt but it's fairly smooth. Looking at the bottom of the button it looks like I may have had a bit of a leak there because the burnt part appears to be outside of the combustion area (IMO). This is the first time I've had the head off seeing this so just looking for some input...

Thanks!

 

[maximusraylius]

think thats what they look like when lean or air leaks .. not enough oilo to keep it from getting the burnt look ... but not exactly sure ..

 

[Bankrupter]

I'd look into tuning. there is a lot of carbon there 4 sure

 

[JKLNHYDE]

Like I said, I may have had a small air leak so I was meticulous when I put it back together today. It just needs to hold out another few runs unil I can order a new mill in a ouple weeks....