How old do you have to be to race in the iditard race?

depends on what you talking about there are thousands of different kinds of "races" with millions of different ages.

In the U.S. it can vary from state to state and even sanction to sanction, I have heard, with parents consent, age 16. There may be some other considerations involved also.

prefferably the 85cc class

if he is just starting then 250 beg

The following is from one of my local motocross tracks, most local tracks should have something similar: 0-85cc 7-15 Beginner 0-85cc 14-15 years 150cc and smaller 4 Stroke, 15 years old &...