Now, can you remove the other panel so we can see how its connected to the fill cap? I'm wondering if you're using flexible fuel line? Now was that "elbow" on the original filler hole just siliconed in? Or did you thread that plastic elbow to screw on to it? One more, what about venting? The original gas cap is a vented..what about your setup?
Roho,
Here is a pic of the routing. This is not a mod I would recommend doing without an experienced mechanic. The routing used the existing opening and with about 1000k on my machine seems to be working very well.