Kickstart gears sound rooted , Gotta make sure you don't just kick the shit out of it. gotta put it in top dead centre every time you kick it over so you don't go crunching gears. You will need to split the bottom end to repair this or replace the motor.
did it initially make the sound the first kick or did it start doing it a few kicks in , chances are he can't start it correctly and has damaged the kickstart gears. Drain your oil out , if you notice an increase in metal spec's then you have done some damage.