Somewhere, somehow, someday, we'll crack the mystical Yamaha paint code!
Plenty have tried before, it's easy to get the Yamaha colour id code. This does not however translate into anything your paint shop can use.
Top results MAY be gotten from using a spectrometer (most good paint shops have them), though you need a good piece they can analyse.
So it's either that, or a top painter with a top eye, or a carefully & respectfully worded letter to Japan. Like I said, the info must be out there somewhere, question is where!