How much heat can the stock NEMA motors take?

Noticed in the store that the NEMA motors call for a max operating temperature of 50C, I’m planning on building an enclosure for the Taz5 and was contemplating whether of not I should insulate and heat it. The stepper motors get HOT, just wrapping up a 40 hour print and the motor heatsinks are almost burning to the touch, aside from watercooling what other methods could I try - bonding another heatsink to the metal casing?

To answer my own question, temps of 40-50C are OK and have not hit the threshold of the air cooled hot end yet, whereas Stratasys level temps of 70C+ will require either the motors to be outside the chamber or watercooling or external air flow via a duct. Food for thought.

I have atleast 500-1000 hours on my steppers in an enclosure, the enclosure internal temp stays around 120f the steppers hover between 140-160f.

ive had no issues. If they fail I will consider water cooling all but the extruder stepper.