those are call mikuni bn roundbodie carbs. there is no stock setting as they were never stock on a 650 motor...and frankly they were a pretty crappy carb....we made em work back then, but that was pretty much all there was. my best piece of advice i can give you is to get a single carb mani and a single 44mm mikuni sbn. you will be riding more and tu ning less. i had a set back in the day just like those and hated them. i ended up throwing them on a shelf and going single 42mm keihin and never looked back.