Original layout was created by me, before 137 made it in the editor.
Supercross track (Video: Devin Davis)
Motocross track (Video: Devin Davis)
And finally, click the image for the download.
This was supposed to be released a while ago, but all credit goes to Kyle Watts for the track. I'm not entirely sure who did all of the objects, but thanks to whoever did them as well and if you recognize anything please give them a mention!