You need to be careful cuz many generator specs are a bit lax in reality sometimes. They can come up short. The Yong Heng will draw more than the 15 amps it is rated for at start up. More like 18amps for a very short time.
Mine recommended a 20 amp circuit minimum. I ran it on a 15 amp, and the breaker blew. So, from a non-electrical type, I'd say somewhere between 15 and 20 amps. Lean towards 20.