There is a new law coming into effect on the 1st September, requiring all scooters and motorcycles to display the small insurance sticker currently Blue for 92 (2003) expiry date.
Failure to display is likely to lead to confiscation of said vehicle, plus a fine.
As many foreignors ride on what are technically illegal machines as they are not registered, then this is will effect you. Without registration, which requires either an ARC or a local girlfriend / boyfriend then registration cannot be completed, thus no insurance.
You have been warned.