The jets normally are not all that is clogged. Try blasting carb cleaner into the jet housing while manually opening the slides and open choke circuit and blast it too with carb cleaner. Check vac line to petcock to make sure its actuating petcock. Prime lets gas free flow so it must fill the bowls and then get cut off somehow? Try running it off another fuel source that you know works(a funnel attached to fuel line will work) Did u clean the float needles and fuel rail out too? Also deff try to replace spark plug asap!