As an example for the cowling here the 350 cc TZ350G (needs repainting !)

1) the red line is 16 cm high, it starts 5 cm under the split where the topcowling is attached and runs exactly over the screw that attaches the cowling to the rearstay.

2)The number plate is 30 cm wide and 24 cm high, there is 5 mm between the red line on each side. The radius/corners on the numberplate are 100 mm diam. From the right the red line is 10 cm wide, next the small gap of 5 mm white, so the blue starts at 10,5 cm from the cowling edge (if you want to be very precise...!)

3) The front number plate on the topcowling has a width of 27,5 cm, the radius differs by model.

Yamaha TZ350G cowling