I know that I have non symmetrical biceps and they both lack a lot of mass too; definetely a weakpoint of mine. my routine usual goes like:
BB curls- 2 warm ups of 10, 2 heavy of 4-6
DB curls (seated one arm's sets at a time) - 3 sets of about 8
Hammers- 3 sets 10, 6-8, 4-6
occassionally some drop sets, 21's etc.
yesturday i did this routine and i thought it was feelin okay but my right bicep is really core and my left isnt really. I really need help!