I have seen many posts here stating the use of large header tanks, 38 oz for instance.
It's been my experience a header tank s/b small, so as not to pick up air.
I have a 2 litre pop bottle tank in my Roo, and it would flame out at half tank or so.
I installed a two oz header tank and no more flame outs.
Seems to me the large tanks allow sloshing of the fuel when it gets partially empty and the clunk is exposed to air.
Probably why some tanks use baffles inside.

Any thoughts on this?