I have watched the karts at Portland International Raceway - they are actually pretty quick in the adult classes. It looks like fun although I do wonder about how rough that ride must be when they use the curbing in the corners (shots 2 and 3) and that can leave you looking for traction once the wheels leave the ground like #4 where at least two wheels are airborne.
There is an issue with Uploading Photos (attachjments). I am not sure what the problem is, and I am looking into it. You can still try to Create your Threads and Upload your Photos, but it is hanging up during the Upload.