NGK Honda Ruckus / Metropolitan iridium spark plug 49cc/50cc
When changing your spark plug it is always a good idea to upgrade to a iridium spark plug. This will result in a cleaner burning engine, in return giving you slightly better throttle response. Performance gains are small (1%-3%) but bang for buck is a no brainer. One of the biggest reasons to switch to iridium is they last about 10 times longer. (This is because it's melting point is 2500 degrees). This spark plug is designed for the Honda Metro and the Honda Ruckus.
If it is in your budget purchase the complete performance igntion kit!