1978 kz650 b2 inside carb bowls fill, but the outside do not, any ideas?

cant get the outside carb bowls to fill. inside bowls fill. any way to blow out the fuel rail without removing carb bank

If the carbs have been off the rack since it was last running then you have accidentally put carb one in carb four position and carb four in carb one position. 
Carb one fuel rail is open on the rh side but blocked on the LH side. Carb four is open on the lh side and blocked on the rh side. So if you've swopped the locations on the rack then you have the open sides facing outwards instead of inwards. 

I look forward to hearing/learning what caused the issue. Warren's solution sounds as good as any I can think of.

I second Warren’s thoughts too, as I nearly made that error when putting them together and easily done if you don’t double check 😁😁