[GriffinRU]

Keep motors and ESC at 70-80C
Personaly if I can keep my hand on motor or ESC for 3-5 seconds then temp is OK, Less is bad more is great (but maybe overkill :))

ESC can handle up to 160C (Based on FET's specs, but not true for microCPU and components inside...) but above 70C efficiency goes south.
Magnet inside motor can handle up to 350C but checking magnet temp is very difficult. And with temp rising heat transfer from magnet to can becomes less efficient. While windings resistance goes up with temp, pulling motor efficiency down.

Artur