I like them. Number seven is my favorite. I think the tight crop is cool, however, it is nice to see a little room in front of the rider showing where he/she is going like in number two.
Sweet shots overall, hope my tip helps, take it or leave it. I'm no pro, lol.
Nice shots! Just wondering if this is your first time shooting motocross? I'm guessing not as these are pretty good.
I like 5,7,8,9 the most. Some flash would have really helped out on #9. 5, 7 and 8 show great expressions of concentration, also #6 but the crop is too tight for my taste.
For me, #1 looks a bit awkward and I prefer to see the ground as well when they're in the air.