Are you more interested in eventually getting compensated for your time or having a piece of a potential larger valuation? Which do you think Jim is more interested in?

If you are primary looking to for the former, you could propose a deal where you get 40% up to whatever you both agree would be a market wage for the effort you put into the startup ($10/hr seems low, but I know nothing of your local economy). That may be more acceptable to Jim, and it keeps you from feeling like you got a raw deal if he has a great exit in a few months.