Many of these twins will blow oil through the breather and into the carbs when filled to the "Max" mark. I leave mine halfway in between MIN and Max and very little oil is pumped through the breather and into the carbs. With the oil at this level in the sump (halfway between) I've seen oil consumption of about half a pint (8 oz) in 1500 miles/2500 km with running the bike often up to 110km/h - 130km/h speeds.
Often, if the oil level is put up or above MAX, oil pumping the breather will be higher until the level is about halfway, at which point the amount of oil consumption will greatly decrease or stop altogether, once the engine has found its "level". Those large pistons going in and out together tend to pressurize the crankcase, especially at higher rpms, which contributes to more oil mist being pumped through the crankcase breather valve and into the airbox & carbs.