i'd just get him a 300 ex

 

If i were u i would look at the Yamaha breeze 125 or the E-TON viper 150R they look like great quads to start off on.

 

maybe you can find an old used trx 125 four wheeler or a 200sx. they can be found for cheap, and when he grows out of it. you can sell it and by then you can get him like a z 400

 

get him this... I think it will be a great beginer bike its not to fast but yet had enough power to get him going
http://trinityracing.com/pages/projects.html























haha jk get him a 250ex

 

I have never driven or ridin the phenox but i think it would be a good starter bike for him , go and have him sit on a bunch of 4 wheelers and see witch one he seems to fit the best on , usualy that will be the one , good luck !

 

i say grizzly 125