Try using Skype. Many hackers are most productive when not constrained by schedule or even location. Startups are hard, especially in the early stages with little/no compensation. Communicate with your partner about what is most crucial for the startup to succeed. If both of you are committed to those things, then it's probably just a matter of finding a way to make it work. Your task is to find out if he's truly lazy, or it's just a lack of communication/understanding.