3RB-012812 is not a frame number for a 250 Yamaha dirt bike; it's a motor number. To find out the model year and frame, you need the frame number.
A Yamaha dealer should be able to help you, I don't know how to read a frame number.
I have a Yamaha 80cc with frame number and matching engine number: G3 116632. I believe this is a european bike because the spedo is in Klm,s and the year is 1964
You find it as a 17 digit number stamped into the frame on the left lower frame rail.
It is located on the frame below your left foot.
Probably a late 70's RD350.
The VIN is etched on the lower part of the frame by the shifter.
The serial number plate is on the front of the frame below the handlebars, behind the headlight. For 16-digit serial numbers, go to the Yamaha web site. For serial numbers less than 16 digits, take the number to a Yamaha dealer and ask for a search from Yamaha Japan.
What model is this Yamaha with VIN number 2YL-035458
find the VIN number on the engine or on the frame then run it through a dealer, or look it up online.
Its between an 81 - 83 model, in 84 Yamaha went to a 17 digit Vin number. Hope this helps. I have an 81 Virago with a 9 digit number on the frame and engine as well.
According to the parts man at Yamaha who I talked with today, the number is on the frame on the left side by the footpegs. This was for a Warrior 350, but may work for your model too. For my Yamaha Moto-4 350 - the VIN is located on the frame, adjacent to the (rear side) of the left front tire.
grizzly