Exhaust leaks and lean mixture?

[Bill2001]

Still tracking down that overheated and seized piston, and looking at mixture. The engine had an old over-reused copper gasket ring at the exhaust nut and a smallish ( 1/8 x 1/2") hole rusted in the pipe about 8" from the exh nut. How prone are 2-strokes to pull air into the exhaust during the scavenge part of the cycle and lean the mixture out? I keep looking and keep coming up with zilch.