Maybe a Honda Z-50 would fit him better as it is very quite for riding near houses plus a low cost & maintenance bike that will run forever. If you
plan on him racing there is a trail bike class for them at some tracks or if racing for sure a KTM 50 air cooled is decent as my daughter had on in 2003
but those require a lot of up keep and are rather loud. Stay away from the Chinese knock offs as they seem to break a lot.
Maybe stop by your local dealer to see what fits him as the sales people could give you some guidance & can shop around from there.
If you are near Amherst try On The Edge as they always took very good care of us.
Don't get anything too large as he will have a hard time riding it as growing kids will go thru several motorcycles over the years.
Also get all the riding gear you can for him as the kids stuff is fairly reasonable & in addition to a helmet & gloves would go for pants, jersey,
boots & shoulder pads.
Don't know where you live as I am in Brunswick but will take a look to see if I have any kids gear left over thinking we have jersey, pants, gloves
& knee pads but need to dig them out.