alt Hacker NewsThey have no driving electronics, electronic throttle, ECU controlled injection etc, so you are limited, you can't for example easily make it go constant set speed, because the throttle isn't electronic.
It went a bit too far, optimum would be modern enough to have drive by wire but with open ECU and documentation
You can still control a completely mechanical engine to work with set speeds. There are mechanical governors that can do this, or you can get an electronic component that moves the throttle for you. Fixed speed engines with variable load are much older than the transistor.
It is no harder than doing it with an ECU, except that you need to install a servo or speed governor with hand tools, instead of fiddling with ECU code.