Heavy
1) 3-4 sets straight bar 6-10 reps heavy as possible,swinging is allowed,but "proper" swinging where you keep the focus on bi's and squeeze the hell out of them during the whole rep range.The negative must be extremely slow.For the 4th set I like to drop the weight and go for real good form,again squeezing the shit out of them.If Im extra insane that day I will do a drop set immediately after set 4.You cannot beat this exercise.
2) Preacher machine.2 sets 6-10reps,heavy as possible,using long negatives,static holds,and 1-2 forced reps.This exercise done properly will break any normal human being.The pumps are INSANE.
3)Standing dumbell curls or hammer curls,heavy as possible with good form.2 sets,heavy as you can go for 10 reps or more.
That is usually enough but sometimes I do...
4)Bent over concentration curls with a short barbell.1- 2 sets.Basically you bend over,hang your arms straight down and curl.Elbows pointing to the floor.This really gives a good finishing touch,lots of blood into the muscle and very painful pumps.
The most important thing for me is to stretch the biceps after EACH SET.You have no idea how much it helps in adding more size to your arms.The fascia must be stretched,which in turn allows plenty of room for growth.
Im at 21 1/2 inches right now and have been at 22".Thats without huge tris,so maybe I'm on to something.........