my frame number which looks to be the same as engine number (which i cant see fully) reads *CJ01C-016722* which is only 12 long
I wouldn't get too excited.
The YZ came from Whales, I assume.
Isn't that part of the UK?
Does the UK have a different VIN standard for motorcycles sold for off-road use than the 17-digit ones we get here in the USA?
The number stamped in that frame looks like what Yamaha
USA would call the "primary ID".
Within the 17-digit VIN of a YZ sold in the USA, there are 11 digits (not counting the dash) that Yamaha
USA and USA Yamaha dealers will use to identify a bike without having to write the whole VIN, such as when warranty registering the unit with Yamaha USA.
So, using the original poster's VIN:
CJ01C = Yamaha code that means YZ-426F
016722 = The number of the particular unit off the assembly line.
I wouldn't be surprised if that's all a UK YZ VIN contains.