1988fast250x,

I have been looking all over the net for the same thing so far I've only found two pages and they're both directed toward super/motocross but they should be a good read for you anyway, they do cover takeoff and landing angles, one by degrees and the other in a ratio, the latter says that quads should use a 3 to 1 slope for takeoff I believe, anyway here they are, good luck and if ya find any other information please pass it along. If you do a few searches you should come up with some pro track builders as well, I came across a few while searching.

http://www.racingsmarter.com/supercross_track.htm

http://www.dirtwurx.com/track_tips4.php