Motor cogging is when the motor hesitate once the throttle trigger is press due to it's inability to rotate due to improper gearing or lack power from a low C Rating battery.
Cogging from Battery: Get a higher C Rated battery that matches your motor Amps.
Cogging from Gearing: Reduce your pinion size until the motor is able to create enough torque to turn without hesitation when the throttle trigger is pulled.