This season, I have not found a TV network that carries AMA motorcycle roadracing events. You can also pretty much forget any of the AMA's short track races showing up on your boob toob.
But there's a new NASCAR-owned live streaming broadcast of AMA races, IMSA sporty cars, and regional NASCAR events that may feed your motorsports hunger. Check out FansChoice.TV on your compuKer.
http://www.fanschoice.tv/And for listings of a variety of two and four-wheeled events, I usually check out TVRacer.com
http://tvracer.com/