Highly recommed the 895 motor:

Still worrying about the power of your 775 motor, the torque is not enough?
A new generation of 895 motors will help you solve all the deficiencies of the 775.

The shaft diameter of the 895 motor is 5MM like the 775 motor. 
Simply replace the motor and the stand to upgrade the power at a low cost. Get started! 
The 895 motor can also be used as a generator. The faster the speed, the higher the voltage and current. 

895 is widely used in miniatures: cutting machine s, belt machines, lathes, milling machines, 
Bench drill, hand drill, polishing machine, bead machine , lawn mowers, wire saws, band saws, electric grinders, engraving machines, scooters, etc. 895 low speed models: 3000 rpm at 12V, maximum torque 5.2 kg, 6000 rpm at 24V, maximum torque 10 kg

895 high speed models: 6000 rpm at 12V, maximum torque 4.2 kg, 12000 rpm at 24V, maximum torque 8 kg .Starting current should be more than 10A. It is recommended to use switching power supply or battery. 

It is recommended to use 360W, 24V, 15A switching power supply, and can not directly use household 220V.
Rated voltage: DC12V -24V (the same motor can use 12 to 24V voltage) 
Steering: Support positive and negative rotation (use positive and negative switch or reverse polarity connection) 

Motor step height: 4.5mm 
Motor step diameter: 18mm 
Motor diameter: 48mm plus magnetic ring 50MM 
Shaft diameter: 5mm (same as 775 motor) 
Motor tail shaft length: about 6mm 
Pitch of mounting hole: approx. 29mm 
Screw hole for mounting hole: M4 screw and M5 screw 
Motor weight: 495g