1979 Honda Hobbit, PA50i

1979 Honda Hobbit, PA50i1979 Honda Hobbit, PA50i
This is my grandfathers old Honda hobbit. I am posting about it in hopes that someone can help me trouble shoot this thing. If I ride downhill on it, it sounds like it started, but then stalls out when there is not throttle response. We drained the tank and cleaned the carb and tried again but still no throttle response. Does anyone know what else I can try? Thank you!