ok the problem with the bikes engine turning over even with it turned off is the starter relay,basically there are a set of contact points inside it and they are either fused together or as bb says the relay is waterlogged and its telling the relay to contact.i have cleaned them before and get them to work again but its not a good fix and willl do it again after a while.look at the battery and just in front of it to the right you will see a yellow relay that is the starter relay pull the plug off the terminals on it and i bet it stop turning over,well it has to as this is where the power comes from ,get a new one and plug it in there and you will see its ok then.the problem witht he bike still running after the igntion is switched off sonuns like a faulty ignition switch to me or a loose wire on the back of it as the low tension coil feed gets sent to earth there so its eithet that or a problem with the wiring loom.
adam bike doctor, March 2010