I find that when flying directly into the sun at the very early hours or twilight hours, the glare of the sun is unbearable. Even with darkly tinted visors, the experience is fatiguing and also makes reading the gauges and GPS challenging at times due to the reduced contrast.
I decided to mod my helmet, MSA Gallet LH250 in my case, with an aftermarket sun visor and thought it would be helpful for other pilots to share the info.
2.5mm Allen wrench (used to remove temple visor knobs).
Drill (preferably drill press).
5/32" Carbide Drill Bit for Carbon Fiber see picture t02 (for more info see this excellent article: https://www.elevatedmaterials.com/drilling-carbon-fiber/
#1 Philips Screw Driver
If needed a screw cutting/terminal crimping tool to cut screws down to the correct length, something like this: https://www.homedepot.ca/product/klein-tools-multi-purpose-6-in-1-tool/1000421422 see picture t01
3 × countersunk 4-40 screws 5/16" length (head tip to thread end)
3 × locking washers (star washers preferably, or split washer)
3 × 4-40 nuts
3 × Male Snap Fasteners. For example: https://www.canadiantire.ca/en/pdp/outbound-snap-fastener-kit-0765640p.html#srp
Aftermarket Helmet sun visor, I got mine on Ali Express, very cheap but shipping takes several weeks: https://www.aliexpress.com/item/Vehemo-3-Snap-Motorcycle-Cycling-Helmet-Peak-Top-Sun-Shade-Visor-Shield-Black/32832586387.html
Similar items available on Amazon with faster shipping but at higher price, for example: https://www.amazon.ca/Core-Vintage-Helmet-Visor-Black/dp/B00F5ZMWLK
Remove Allen screws from visor adjustment temple knobs. (Picture 01)
Pry gently both temple knobs away from the helmet and swing up the outer visor guard it should then be able to lift up out of the helmet. (Picture 03)
Mark the location of the 3 snap fasteners along the bottom edge of the guard.
Support the visor guard with scrap wood on the drill press and drill the 3 holes.(Pictures 04 & 05)
Drill the 3 holes. Pictures (Pictures 06 to 09).
Attach snap fasteners with hardware. (Pictures 10 to 13)
Reattach outer visor guard on the helmet. Attach the rear part with two pins first (picture 03) then swing the guard down whilst pulling temple knobs out slightly. Once the temple knobs are in the temple holes, you will need to rotate the knobs slowly until they "click" into place. Then reattach the temple knobs screws using the 2.5mm Allen wrench
Sun visor can now be easily installed on the helmet. Pictures 14-15