Having seen many kids learn to ride, i'm gonna toss my opinion in here.
Things to keep in mind.
He's gonna crash the thing 50 times in the first day if he's a daredevil like most of my friends kids.
The cheap chinese machine costs 250$, won't go very fast, will be lighter to pick up and once he's a better rider you can give it away.
As long as you keep oil in it and don't overheat it, give it some cool down time on hot days, they provide plenty of fun.
Those 110cc bikes are tall enough for a 7 year old and will go fast enough to scare him.
If he's still interested next year, buy him a better bike.
Most important, a bunch of gear, shin guards, elbows, plus the usual moto stuff, helmet, boots, eye protection etc..you won't believe the crashes they somehow manage to get themselves into. :lol: