So, you joined, found out that you can do this, now you have CTO of a small company on your resume. Which does mean something. It sounds like you've gotten out

So, you joined, found out that you can do this, now you have CTO of a small company on your resume. Which does mean something. It sounds like you've gotten out of this employment what you originally wanted. I think this is the point where you need a transparent conversation with the owners about your role, and your future. Make sure to structure it in a non-adversial way, and make it something along the lines of how you see all these possibilities of improvement that could yield great results for the company, and that you'd really like to work on it more than just the 9to5 to make it happen, but not having skin in the game to reap the full benefits of your work when it will inevitably bring in a lot of money is a mental drag that you'd like to get rid of. Be prepared to talk numbers. Have an idea in your mind of what you're going after. Be prepared to have it negotiated as an options agreement. E.g., that you buy it with your money at some valuation. Be prepared that their offer may be insulting to you. Be prepared to move on in case it doesn't work out. This is really in a lot of ways about what kind of a relationship you have with the owner(s).