No title is needed for a motor, just the boat. However, get a bill of sale when you buy it.
I am in Texas
I'm also in Texas. My boat is registered, but not titled. It was not required at the time I moved here (1992-ish). None of my outboards are titled. What are the ramifications for not having titles, particularly when on the water? The boat can be titled easily, since I still have my original Florida title, but I have never had titles for the motors.