Battery Help

I just recently purchased an E-bike(Lee Iacocca Model) it's a 24 volt system. i was wondering if I calls for 2 12v8ah batteries. i was wondering if i can use higher ah batteries without causing damage to the motor? Or could i use 4 battery's in 2 parallel to the first 2 to get greater distance and power?

Regards,
AardenKaas