Whatever it is, it will need to be easy to rememer / spell so that it can be verbally given to people we encounter on meets.
I would LIKE to ideally keep it international, but that isn't a huge deal as this will be primarily UK based...
r125forum I quite like.
Yamaha125.co.uk is a possibility, or maybe yamaha125.com
I suppose Yamahar125.co.uk would be taking the piss a bit TOO much?