Yeah if they have the right size dirt bike and gear
between 150cc and 250cc
a 120cc dirt bike is suitable for a 17 year old
I would perfer a Honda CRF 50 there a very great 50cc training bike
an exercise bike would be the best start
no you have to be at least 14
Yamaha XT250
Yes
Try a Yamaha TTR 125 or CRF 150 (not the motocross version).
No.
A Yamaha 125
a xr 100
For a 13 year old it depends on your size and your experience with dirt bikes, but an 85 is usually the best size bike and fastest for a 13 year old. Unless you are really tall which you would need a 125.