Put a gas jet in it, about .033, probably need the screw 2 turns out, won’t respond well at 1 1/2. I break my flatheads in on gas with same carb for methanol, needle valve screw is touchy until you get crisp throttle response
.034" jet is stock. If it's been a WKA/IKF build previously...change the jet out for a .036." If the carb bore has been made bigger, and the rest of the engine built up, you'll need to start out there. Most of our WKA engines can be run on gas with a .037" or .038." As said above, the needle is very sensitive with gas, unlike alcohol.