I was going to suggest a bigger cone too, how big is your Yorkie? Petco and Petsmart have different cones, maybe they have a bigger one. Also, after neutering surgery, my vet said to use clear roll-on antiperspirant around the wound, if a dog licks it, he gets a very bitter taste. This discourages some dogs. One like this may work.
Buy Mitchum Roll-On Antiperspirant & Deodorant, Unscented & More | drugstore.com