Here is what I would do if that cylinder came across my bench, first I would remove all the studs they will be nothing but in the way, then I would get out a plastic tub and break out the muratic acid, a old tooth brush, a small plastic cup like a cap off a spray can, then put about 1 table spoon of acid in the plastic cap then put some on the cylinder wall to dissolve the aluminum that is smeared on the cylinder wall, rinse repeat until ALL the aluminum on the cylinder is gone.
Do you need a safety speech about working with acid in a well ventilated area and all the hazards involved, you can read and UNDERSTAND all the safety warnings on the side of the bottle ? You will have plenty of water ready in case something goes wrong, you will have a box of baking soda at the ready, face shield, well ventilated area all that good stuff or are you a moron and will need to take a trip to the emergency room then hire a lawyer lmao.... Plan for the worse hope for the best.
After all the aluminum is removed I would then hone it with my ridged hone (not a ball hone or spring hone) to see what the condition of the cylinder wall is if its worn even I will continue to hone it until its ready for a new piston then I measure the bore and look in the manaul to see if the cylinder bore is with in spec for that bore size.
A example of what I am talking about here
http://pilotodyssey.com/PO/viewtopic.ph ... ight=an112Another example of the ridged hone on a 4 stroke
viewtopic.php?f=24&t=5479&start=25Here is a bore inspection on a TRX250R
viewtopic.php?t=2404Another bore inspection
viewtopic.php?f=1&t=5468If the cylinder still looks straight its then time to measure it as outlined in the manual go from their.
Tell us more about your Pilot and its modifications, how long you owned it how long since last rebuild, what happen that caused the poofkaboom, , any jetting info more details the better...
Looks like the cylinder has been ported to me.