Look carefully the hose that is attached to the frame via a hose clamp is the drain... unscrew the hose clamp and pull the hose off, this is a stopper which you will see when you pull hose off, and understand their thinking.
Level the bike to get all the oil out and, as aforementioned take the oil cap off so the air can replace the oil leaving the tank, this shouldn't be necessary, but do it any way, meaning take tank oil cap off. P.S. the hose from the tank is not braided and is the back hose on the right side of bike on a Chopper. Probably have to unscrew this hose clamp from underneath the bike, it goes without saying "Have a drain Pan ready!" Don't overfill the tank, or the air cleaner will start wearing the extra oil from the tank, meaning it will suck it up from the head-breather of the engine that is connected to the air filter. The tank vent can't be submerged with oil this will happen when cold oil expands when at operating temperature, so check oil only when at hot most people will fill the oil tank when cold, don't, or you will put too much oil in, plus it will leak from the tank breather filter near the back wheel.....
If you put too much in... suck it out.....In my opinion a little low is not a bad thing, it's a remote system so, as long as it can get oil everything is okay, if a quart low the oil operating temperature will rise.
Its not all that touchy, but always keep an eye on it. The oil level when the oil is cold will be lower than hot oil, check when hot.
