Hooray for the primer bulb!
Without the bulb plumbed right below the filter, I'd be siphoning gas to both tanks. Squeezing the bulb, it takes a few minutes to fill each tank on flat ground. No need to run the bike up the tree anymore to fill gas every 10 miles.
Still a lot of air in the system. First I'll remove the brass elbow, run a straight 1/4" fitting and insert the 3/16" steel line and a 6" hose.
The extra parts are laying around somewhere, and will save me another $15.
If that doesn't work well enough, I'll drill the tanks and install vents.