Odd question
 

I know it seems simple, but I'm checking for a friend because he's driving and can't look it up (and I have a 10 year old f4, so I don't know!)

Is the left or right headlight on for low beams?

Neither. I am pretty sure the F4's had a single headlight with a 2 filament bulb for the high beams. If it's an 01 F4i then the left is the low beam and the high is the right. And thats if your looking at them from the seat of the bike.