Headlight reflector thingy

[Fazerider]

Darrsi is correct, the shroud over the H1 bulb will come out through the hole for the H4 on the right.
Without it there is a fair bit of glare, I rigged up a smaller replacement from a bit of metal cut from a beer can.
Alternatively, it’s possible (with a lot of work) to enlarge the hole and make up a mounting plate to fit an H4 bulb to make the left match the right.