We have the same problem however he is getting better. He is now 5 months old. Yorkies do not like to be ignored and I found that if I tell him "no biting" and he still does, I quit playing with him and put him down. He will talk back and sulk but it does seem to help. I was also told not to play tug of war with them as that encourages the biting. Seeing how that is his favorite game we still play, but we have toned it down a lot. Good luck.
