My experience is that the enamel on the motor windings usually burns first, then yous gets the smoke. Personally, 160F is pushing it for me. I like to keep it in the 150Fs. Remember that the motor can is much cooler than the innards.
Team Associated | Reedy | Airtronics
RC Excitement: Fitchburg, MA | RC Madness: Enfield, CT | Horsham RC