Sorry, Lobo - I haven't messed around with the carbs on the G/S. It came that way, so that's the way it stayed. It was set up by a shop in SF (think it was named Darwin Motors) that converted it to a liter. They evidently did a good job.
When I've gotten that good mileage it was riding the freeway to southern Oregon to visit friends - 300 some miles. I'm generally a bit faster than the rest of the traffic, but keep a steady pace and try to stay in the range where I won't get tickets. I'm not much of an 'on-and-off' the throttle kinda guy. Also, I'm probably 165 or 170 pounds geared up, so that makes a bit of difference.
In the rough stuff and logging roads where I'm in lower gears all the time the mileage drops - sometimes in the high 30s.
SS - Wonder what sort of mileage yours would get at a smoother pace? I understand it's a badge of honor what lousy mileage you get.
You're obviously one terribly fast sumbitch! Ever think of taking it to the track?