Not sure I follow your logic. Who is saying there's an upper limit of 200cc for registration? Fuyang or Xiaoshan? Or Hangzhou itself? If Hangzhou has banned bikes, as it has, it doesn't matter where your bike is registered; it's not welcome. My Shanghai-plated Jialing is not welcome in Hangzhou, though I've passed through several times -- bang through the middle of town -- with no issues. (In fact, it may be that I was not hassled precisely because I was displaying an out-of-town plate.) I can ride my Shanghai-plated bike anywhere in China where bikes are allowed, so why would you not be able to ride in various areas of Zhejiang on a JH600 with plates from, say, Anji, or perhaps Ningbo (perhaps with help from bikerdoc, who has plated numerous bikes in some district there)?

I also don't understand the logic of registering a 250cc bike if the upper limit is 200cc. Go for the JH600, and get legal plates in some jurisdiction where this is not an issue, then ride the bike you want, wherever you want (subject to local restrictions).

My 50 fen worth...

cheers