how did it get that way to begin with? ufo in the chamber or something...I would clean it off with a fine file or emory and run it but would not feel confident till I found the cause of the condition first.
I cleaned it up some.That's about as far as I want to go.I cannt remember,I dont think it had an oil cooler on it.Could that of been the cause?When I took the engine apart,other than that one piston, it looked real clean.Crosshatch pattern still in the cylinders & all.No other part shows any wear at all.
the rings are what makes the seal.. if there is no damage to the ring lands, hone the cylinder and run it....ive ran worse and had them last for years.. you do need oil cooler and check and make sure middle carb is not running lean..... my 2 cents
+1 Not sure what it cost, but can guarantee it will cost much more if it lets go once it's all back together. I've done that before. Spend the money so you know its correct. There will always be other shit to worry about.
Looks like classic signs of detonation starting to eat away at the piston. Detonation usually takes place near the exhaust valve at the edge of the combustion chamber (hottest place in chamber and poorest-quality fuel/air mix). You may have been on the verge of disaster there.
That piston looks like a hi-comp piston. Better check to make sure. Hi-comp Triumph engines running on pump gas with their old-fashioned combustion chambers are prone to detonation — especially on the triple's center cylinder. On a street triple that you want to get a lot of use out of, I'd recommend using the stock compression ratio.
You definitely want to run an oil cooler. Although they are called "air-cooled" engines, the oil does a huge amount of cooling as well.
And of course, make sure the timing is exactly what the manual calls for.
As far as reusing the piston, better not to. Detonation is a real piston killer.