Are you looking for a kit, or just general knowledge?
Aside from the gens with a Honda motor, which have a fuel pump already, the rest are gravity feed.
All the kits I have explored seem rather generic. The key item they're all built around is a vacuum powered fuel pump. This pump can be found inexpensively on Amazon. The next step is finding a vacuum line to tap into. That knowledge is what makes the kit expensive.
Without a fuel pump, I've had limited success with gravity feed siphon for my Yamahas. Either the siphon breaks and no fuel is delivered or there's the tiniest of air leaks and too much fuel is delivered.
2013 KZ Sportsmen Classic 200, 20 ft TT
2020 RAM 1500, 5.7 4x4, 8 speed