Hi Jasper,
I did a google search using "Honda CRB 600 voltage regulator"
Lots of info,
This is a cheap fix,
http://cbrforum.com/forum/showthread.php?t=27739#199676
It came from this thread.
http://cbrforum.com/forum/showthread.php?t=25952
Good luck,
Mike

Be careful, these forums can be addicting :-)