I've been gravity bleeding brakes for years, here's how I do it;
Get the car in the air with the wheels off.
Take the cover off the M/C.
Open a bleed screw and let fluid run out until clean fluid comes out, keep topping up to make sure the M/C doesn't run too low.
Repeat on the other 3 wheels.
Top up the M/C and replace the cover.
Check to see if I have a good pedal.
Refit wheels and road test.
Roger.