What was your role in co-founding the company? No offense but it seems like John is the one who engineered the technology.
I don't know either of the co-founders, but it seems like a logical, good idea to have a pair of co-founders where one is technical and the other is non-technical (maybe marketing, or sales, or very strong soft skills, etc).
Hence, I don't see the issue you (obviously) have with only one person having done the technical work. Is there any context you're not telling?
As an engineer, I've been approached by those experienced in sales and offer me to build a mutually agreed upon product that we agreed would make money for equity. I would like to know if this model works. If so, how does it work? Is this common?
You can take offense if you like, but if you meet a guy at an entrepreneur conference who already built a prototype, you're not a co-founder.