I see a lot of shit cobbled on motorcycles. Especially custom-built bikes. It's easy to start nearing-the-end of the build, and corner cutting begins to get this thing goin'. I'm at that point now. Struggling with fuel lines, and trying to stay on task, and DO THE SHIT RIGHT. I want to run the original type oem solid, cadmium plated fuel lines. (see above)
The Left Tank runs this later model (rubber seal type) seat for the fuel rod. The large banjo fitting feeds the fuel from the Right Tank. The caps are both vented. Did you know early, original fatbob tanks don't have that center top crossover vent tube? Both gas caps are vented. I want the crossover line to sit flush without binding. No stress. All the sealing faces to align square and true. No twisting when tightened.
The fuel turns on by unscrewing this knob on the Left Tank. The rod end seats into that fitting on the bottom(previous photo) and when you pull up on the rod, it allows gas to flow to the carb. If you pull the rod all the way(as shown) it opens up a lower hole to allow all your gas to the carb (the reserve supply). There's no petcock on the tanks. Turning the fuel on and off from the driver's seat, no reaching. Just pull up the fancy chrome knob for Harley's patented: "Instant Reserve"
It acts like a giant needle & seat ! The original rod (top) is just steel. Carl's Cycle Supply offers a special tipped rod (for improved seal and no leakage). I lapped in my original steel unit, tested it, and it seems to seal fine.
This clear line (above) can get hard, brittle - and usually starts to crack and leak right at the fitting. The only advantage I note - is you can see the fuel. It's easy to melt too(don't let it touch a cylinder), etc.
The point is: Don't hurry. Take your time and do it right. Wait if you have to.
Another saying I like is: "Good Things Come To Those Who Wait."