They do make a 350cc Version, Same bike but with the 350 lump in it.
Before I got rid I had a fella on my Facebook who had put a 650 in his, Don't think I'd want to trust that frame & brake set up with a 650 though.
You are right though Tefal a 250 would be perfect & I did look around for a Super dream, Nice lazy twin 250 like that would have suited it sweet with some cut down pipes.
i want something small light and indestructible for winter i don't want to be taking the vfr out in the frost every day for work.
it's only about a 10min journey so was thinking a 125 or something.