Ya been their done that! Buying used motors is hit and miss and todays brushless motors last forever so my question is why is he selling? If it was a 13.5 or better safe to say its ok but a hotter motor 8.5 id buy new myself.

Ive just recently learned my lesson after buying a 30 dollar brushless used motor!

On the other hand why do you want a 4.5 geez thats to much motor!