We found a photo of the Go-Bowen 24V 350W Sonora ATV's motor, chain, and axle sprocket and it looks like the back of the motor is almost touching the brake rotor. A gear motor that will produce more torque and speed would be larger than the original motor so it may not fit in the original motor's location unless the brake was moved or the motor was mounted somewhere else.
We are only looking at one small photograph though so maybe we are not seeing everything. We recommend taking a look at the ATV in person and seeing if a larger motor could be installed and how to go about that.
Once where or how to mount a larger motor has been figured out then we can help with selecting the larger motor, sprockets, controller, etc.
Another option to replacing the motor with a larger one is to overvolt the original motor. However, when overvolting a motor from 24 Volts to 36 Volts it sometimes runs cool, and other times overheats and burns out, so that is a risk you would need to take if you are considering overvolting the motor.
Either way, we can help though. Please let us know if you have any questions and we can take it from there.
Thanks for attaching those photos. There is actually a lot more space around the motor than we thought there was.
We have a 24V 450W gear motor, however, that is only 100W more than the original 350W motor so maybe our 24V 650W gear motor would be a better choice. I attached a drawing of the 24V 650W gear motor's dimensions so you can check and see if it will fit in the ATV.