wow, surprised no one has replied yet... I rode it last year, and keep in mind my recount will be from a beginner's perspective.
This was my second ever race (the first being the HHORA Family Fun Scramble). I was riding a '00 CR250, stock motor & suspension. This was not a fun combo for the terrain. Actually, the motor wasn't the problem, it was the suspension. This was a rough course. Portions of the course took you through dry creekbeds, consisting of fist-mellon sized cobblestones. There were a few high-speed dirt roads, you got to go on the MX track, pretty much everywhere at Hangtown. They had a sand track laid out about 3/4 of the way into the course, and that was a real blast- probably my favorite section.
The start was dead engine, by class. By lining up all the way outside, I got lucky with a really good start. That didn't matter much a few mintues later, as the course funneled through a small gate- talk about bottleneck city! It seemed like the entire field arrived at once. Guys were bumping, cutting, you name it. The poor course official had a tough job threading bikes throught the barely handlebar-width gate without getting run over himself. After that things pretty much spread out and passing/getting passed (me) was easy. Beware of a few blind drop-offs (some over 6ft) that sent more than one over the bars. I think I remember there being lots of vertical inclines/drop offs everywhere, which were challenging for me the first time around the loop.
I made the whole race on one stock tank. If your 310 is thristy, you may need to pit (unless you have a large tank). When they waived the checkered, I was releived that it was over, yet at the same time I didn't want to quit. I was getting really worn out having to stand so much (my butt was too sore to sit after the first lap & a half), but it was still fun. If I still had my bike I'd definately do it again! You might be able to find photos from last year's event on the D36 website. Others here like enduro8 and angryjim can give more detailed/racer oriented info.