I liked "mrmunsell" bike so much I had to replace my old sad looking windscreen.
I installed a new OEM CBR250R windscreen a couple of weeks ago. Had to do a little trimming to make it fit.
First put some blue painters tape or something similar along the where you will cut shield.
The top of the screen is flat, so I made a mark at top center, then I made a mark 3" on each side of the center.
Next I measured up 4 5/8" from highest point of upper cowl and made a mark on each side. Now I used a big oil drain pan with a 18" radius to connect the side marks to the top marks.
I used a sabre saw w/fine tooth blade to cut the radius, be sure to have tape on shield or under saw. after cutting radius's you will need to cut the thick bead left on the top 6" edge.
Next I used a rasp, then a file and lastly dragged the edge of a utility knife along the edge to smooth it out.
Put a towel or something over dash to keep saw dust out of everything.
Your results may vary depending on how bars are adjusted
I installed CB300F mirrors a couple of months ago, now I can see that car that likes to stop 6" from my rear tire while I'm stopped at a red light.