New Build, New problems, need help.

[Kitwn]

Sounds like a Longs or Wantai drive kit.
Had the same characteristics on my old X2. All still works.
I put it down to the highish inductance of the cheapish motors.
It's not like you can set the driver current too high for them and burn them out!.

There's no heat generated in inductance, but higher inductance might be due to a larger number of turns of finer gauge wire which will increase the resistance of the winding as well. Heat is generated in resistance (RMS Amps squared x Ohms) so there might be a relationship there. Motor specs include the resistance as well as inductance so you could make a subjective comparison of which motor might run hotter for a given current, but there are other factors that will affect the true RMS current drawn by the motor anyway. As always there are several worms in every can!