Official update on the rules:
"You can put your 200cc motor into anything you want. Make sure it's just a 200 or it will have to be at least 30 years old to put a 225 in."
and another comment from someone who's done it a few times:
"Well, as long as it's 200cc, you can do pretty much anything as far as modify it
for the event. If you were going to boost it to the "vintage" limit of 225cc and
run it as vintage, it would also have to be in a frame at least 30 years old. I
think it was discussed some time ago as to what determines whether a bike is
vintage or not, the engine or the frame. I believe that Bill's ruling on that
was that the bike would be considered vintage based on the newest part, whether
engine or frame. In other words, if you stuck a '76 motor into an '88 frame, it
wouldn't be vintage, based on the frame. But then again, maybe I'm full of E36 M3
and it's based on engine alone!! My wife would agree with the full of E36 M3 part!
What kind of modifications are you talking about?
By the way, welcome to the jungle!!!!!"
I just need to figure out which 2-stoke is going to give me the most bang for my buck. I'd really like to stick with the EX250 frame idea; I'd imagine a full fairing is exceptionally nice on a 12-hour race.