Motorcycle Repair: unknown yamaha engine, mid seventies, resorses

Question
Do you know what engine this is?
i just purchased this on ebay and am going to rebuild it, but don't know anything other than that the seller said it was a 70's model Yamaha 200.
Pictures are here:
http:/stardogg.wirefire.com/engine.jpg
http:/stardogg.wirefire.com/engine1.jpg

Thanks,
-Brett


Answer
Brett,
 This is definitly from a mid seventies or prior RD 350 or possibly 250.  You will see cast into the base of the cylinder or in the case itself, a cc size.  I'm suprised the seller didn't make clear what it was, this is a very popular bike to restore for vintage racing or show.  There are many bits of info I can tell you regaurding the rebuilding of the motor as well as resorses for parts and machining.  Write back and let me know what you plan to do with the engine and how far you are willing to go, I'll be happy to help.

Mike