I used 5/16" hose & QD's on the tank I put together, and it works great...
I don't believe you have a high enough fuel flow with the fuel 'sipping' Honda's to warrant a larger hose...
From an earlier post:
I used one of these: Honda EU1/EU2 Ext Run Gas Cap
http://www.wisesales.com/honda-eu1-e...l#.UNPRettsKCd to make up my own extended run fuel supply...
I used two fuel hose quick disconnects, one at the tank, and one at the cap so I could pack the components easier...
Also, I mounted one the quick disconnects opposite of the other so that the fuel tank would be 'closed' when the hose is disconnected, and then I could hook the hose end together to keep the hose 'sealed' during transit - after draining all fuel back into the tank...