I bought a "temp-gun" today.

[E-Revonut]

From what I've seen 140 is the max safe temp for lipos. On the motor it's nice to see 120-140 but on my truly I regularly see 140-160 when I come off the track, I'm geared pretty low to keep from going crazy on the track, 180 is max though. On the esc if it is a CC product and it thermals something is wrong, otherwise I wouldn't worry about it to much. It's hard to get an accurate reading on a MMM with the plastic casing around it but a true reading on the heat sink shouldn't really ever be above 160 IMO, I believe thermal shutdown is around 185