I am sure your boy is really sweet and beautiful and has alot of great qualities, but I would not breed him. He is by far too big. Not only will you have an impossible time finding a female for him, but finding a home for the puppies would also be a big challenge. Most people want the standard size yorkies not ones that are going to be alot bigger, and like someone said, I have seen alot of big yorkies end up in a shelter because they got too big.
Another thing to consider... You said your boy is very loving, sweet and gentle. If you want to keep him that way then don't breed him. If you breed him, chances are you will have a boy with a different disposition with only one thing on his mind, just ask several here that have a male that has been bred.
Neuter him and just love and enjoy having your boy as a sweet, lovable, good companion. He will be much happier this way and so will you!!
