yer you can still ride there just about a third of it has been fenced off, cutting out parts of the 50 track, but its not too bad for big bikes, you can still ride all the tracks over the other side of the road which are pretty sick for big bikes , maybe not so good for the 50's.
Theres a few little tracks out near port gawler off road hire park, not in their property but on the outside of it, saw a few guys out there riding last weekend looks like theres some descent tracks out ther you just have to find them....