A $15\: kW, 230\: V\:dc$ shunt motor has armature circuit resistance of $0.4\: Ω$ and field circuit resistance of $230\: Ω.$ At no load and rated voltage, the motor runs at $1400$ rpm and the line current drawn by the motor is $5\: A$. At full load, the motor draws a line current of $70\: A.$ Neglect armature reaction. The full load speed of the motor in rpm is _________.