If you are currently running at a sprint track, in Junior Super Sportsman (2004 IKF National Class #5), the most likely road race crossover classes are...
 
 

IKF National Class #4 - Junior Sprint Sit Up Light

 
Rule Differences...
 

Age:
 

13 - 15 years of age.
 

Weight:
 

290 lbs
 

Brakes:
 

Front brakes are optional.
 

Tires:
 

No compound or manufacturer restrictions.  5" or 6" rim diameter.
 

Intake:
 

Air filter may be used, in place of an air box, unless local authority mandates differently.
 

Exhaust:
 

Any version of RLV SSX muffler (4-hole can).
 

Race / Heats:
 

30 minute race.
 

IKF National Class #5 - Junior Sprint Sit Up Heavy

 
Rule Differences...
 

Age:
 

13 - 15 years of age.
 

Weight:
 

310 lbs
 

Brakes:
 

Front brakes are optional.
 

Tires:
 

No compound or manufacturer restrictions.  5" or 6" rim diameter.
 

Intake:
 

Air filter may be used, in place of an air box, unless local authority mandates differently.
 

Exhaust:
 

Any version of RLV SSX muffler (4-hole can).
 

Race / Heats:
 

30 minute race.