Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
Never had a problem changing a engine number, CC or Vin on a bike
In part it's trying to prevent illegal vehicle id changes, ringing, in other words. I was looking at cars for a niece, one of which was an uneconomic category for repair after an accident which she wanted. I was wary about lumbering her with something wrong and spoke to Vosa about it (which convinced me to avoid as too many concerns couldn't be cleared) they just want to see a logical / traceable path through the identifier parts to avoid fraudulent changes.