I've got a CB 500, had it for a year in london. Brilliant, really cheap, i've been crap on the maintenance, and it has never had a problem.
It's a 1996 on an N-plate, with 20k on the clock. really reliable, really cheap, handles quite well, breaks well and goes ok. great bike. get BT45's for tyres, great wet grip, and good life. email me if you want to know more.