14 years old should join the junior kart program - I think both CIty Karting and KartQuest have them, but of course must pay. But he must learn quick coz 12-16 years old are racing the 125cc Rotax Max Junior which is freaking fast and it would take a novice quite a while to get used to the power of the 125cc. Take your brother to watch some kart race and see the little fellows (below 12) in their souped up 80cc cadet karts!