There is really no such thing as a site title (as far as google is concerned) other than the domain/host name like www.yourdomain.com.
In the html for a page there is the <title> element which is the title/name for the page and there may be headings h1 to h6 for sections on a page. Sometimes the mojoPortal "site title" is used in the layout.master of the skin with an h1 element but nothing really tells google that this is a site title, to them it is just a heading on the page like any other heading and it may not be shown unless it is relevant to the search terms.
You should make sure that your important pages all have the <title> populated and they should all also have a good meta description. Usually google will show the <title>, the domain/host name, and the meta description in search results.