My friend tells me that the Runaway Bay track
is okay for pocket bikes, and its FREE! The track is rather open with no real sharp turns and is about 1.3km long. It's on Oxely Drive, here's a picture from Google Earth
Speaking of GE I seem to have an eye for these tracks. I've managed to find 7, the hard part is always finding out what they are. I was looking forward to going to one particular one until I found out it was Parklands. Anti-climax...
EDIT: Forgot to mention, I've emailed the kart tracks, waiting to hear back.