When did Yamaha stop updating the YZ250 2 Stroke?

[MikeT]

I have a 2000 YZ250 and am tentatively looking into selling it and getting a newer YZ250 2T. I know they have went to a BNG (Bold New Graphics) approach each year with the 2 strokes and I wanted to know when that started. I know they made a good suspension upgrade in 2006 but has anything of significance happened since then? What I am after is what year are the bikes the same but just with graphics changes? Is a 2006 YZ20 the same as a 2018 YZ250??

 

[MikeT]

Ok, narrowing things down here. Main question. Apparently Yamaha says that the forks are different on the 2015 YZ250 than the 2014. What is the difference? They are both the same outside diameter, so what has changed on the inside? Just revalved or what? If I buy a 2014 to 2006, can I have them revalved to be like the 2015?