Depends on ur age, size bike and how good u r.
Practise and practise. Push your self and you will get better and better and then you enter motocross races and if you are good you could get sponsored.
They would have to be in a 90 cc class or lower to race quads. But you can be any age to race dirt bikes.
65cc 85cc supermini
brad lackey
The KTM 50 is suitable for Motocross racing, and is deemed one of the more standard types of racing vehicles amongst motocross racers, as it is a lower class racer.
125, 250, 450
prefferably the 85cc class
if he is just starting then 250 beg
25+ vet A and vet B or 40+
there are many here are some: supercross arena cross motocross freestyle motocross indoor motocross outdoor motocross
Depends on the track, some tracks have a class for pit bikes to race in.
Motocross, Supercross, Arenacross, Freestyle Motocross, Supermoto