This is my second season of shooting Motocross and Supercross in Wichita KS and I'm hooked! I've also been working on playing around more with composites and actions in photoshop. Last year I made trading cards and parents/riders loved them and I sold quite a few. This has been fun. Glad to be part of this group! I'm currently shooting with 2 different bodies, Canon 7D Mark II and Canon 5D Mark IV. Most of the time I have my 70-200 f2.8 on the 7D and a 24-70 f2.8 on the 5D.
I like the way you're composing your shots a lot, but definitely need to work on getting them a little more sharp. the auto focus on your bodies should definitely be fast enough and I don't think that's the problem. I think your shutter speed is a little too slow. Using a slow shutter speed can give some cool looks but when the rider is slightly soft and the tires have motion blur it looks unintentional.
On the other hand it might just be the photos I'm seeing here. The photos in the motor sports section of your site have sharp riders.