Make sure you're running the same mix ratio as the previous owner.
Then I'd start with a new plug. Check that the air filter isn't over oiled and nobody left a rag in the airbox, check the silencer to make sure it doesn't have an obstruction inside.
Pull the nut off of the bottom of the carb floatbowl and make sure the main jet hasn't fallen out (trust me, seen it).
Welcome to the forum; let us know what you find out!