The dirt bike rider kicks up dirt as he turns.
The rider is in a race.
The dirt bike rider isn't necessarily in a race just because he is riding a dirt bike.
exists e1 p1 s1 x1 x2 x3.(exists e2.(Actor(e2,x1) & v_turn(e2)) & n_male(x1) & as(e1,p1) & a_up(s1) & Manner(e1,s1) & Theme(e1,x2) & Actor(e1,x1) & v_kick(e1) & n_dirt(x2) & n_dirt(x2) & n_rider(x1) & of(x1,x3) & n_bike(x3) & of(x1,x2))
exists p1 x1.(n_rider(x1) & exists x2.(in(x1,x2) & n_race(x2)))