Removal of the carbs is almost the same as the 600, just remove the plastic tray over the carbs which holds the coils.
Remove the two plastic rivets which attach it to the frame and pull out the drain hose with it.
Take note of how it locates first, don't lose the rubber funnel attached to the tray which funnels any fuel or water from the top of the tank (same as the 600).
400 Carbs are Kehin, 600 carbs are Mikuni.
Just be aware clutch plates are completely different to the 600, but EBC do a set code CK2371.
Carb inlet rubbers and down pipes for the 600 fit.