Simply put, if he's not carrying his weight and doesn't seem passionate, kick him off of the project and return to doing whatever duties you assigned to him yourself. He clearly doesn't care much about it, and from experience in a very similar situation, no amount of speeches will impact his motivation in any long-term way. You're simply opening yourself up to more disappointment and frustration, not to mention potential ownership issues by continuing to allow him to come along for the ride. As harsh as it sounds, this is why people don't go into business with friends, unless you are completely fine with that friendship not lasting on the other side.
I've been in that situation but luckily even having spent only 50 hours on the project we had something written down on day one, basically a '50:50' agreement, signed on paper. Get something written from your future(?) cofounder, especially if he's given up. A couple of years in the future you might have success and he can come back and claim part of it. Like in the movie 'the social network'. Justified or not that would cause trouble and costs regardless the outcome.
Can you purchase his share for a small sum? $100 USD is worth it as long as the other party agrees and gives something in return. And such an offer certainly gets the discussion about ownership and time-spending started.
He's flaking on you. Don't waste time or enticements for him to change his ways.
Better that it happened now than one year from now after the company is incorporated with his name on the paperwork and nominal ownership established.
Doing business with friends and family is almost always a tricky proposition.
People tend to have expectations that go beyond just business.
you wouldn't have posted this if you didn't already know it's not going to work out!
You are just doubting yourself: you will learn to trust your instincts and make hard decisions because if you don't then your business will suffer.
Better to pull the pin early and be 100% clear and don't gift them any equity. Delay and dilly-dally will just create a crappy situation in the future. Future-you will appreciate problem prevention and that you didn't punt the problem for later.
A co-founder MUST be strongly self-motivated. Motivating is what you do for employees and you would soon feel resentful if you follow your current path. If they are not motivated then you can't do it for them.
Also beware of anything that demotivates you: it is dangerous and I have seen that play out badly. Carefully feed your own motivation - self-motivation is an extremely precious resource that is easy to fuck up.
Keep your friend and don't mix business with your friendship. If they are a good friend they will still be a sounding board, and a good friend will understand your reasoning and won't be a bitch about you going it alone.
Equity is not a gift to just freely give away - husband it carefully.
Disclaimer: not an area I'm an expert in - just an engineer.
Trust in yourself.