I took the square 4 for a blast on new years day covering over 70 miles at speeds between 50 and 70mph
On the way home I had to hit reserve despite having a good few gallons above the reserve line prior to the journey. I estimate I was getting around 35MPG or so.
No leaks - not an overly rich mixture and nothing daft like brakes binding and so on.
I know the solex carbs aren't great but would those mpg figures be acceptable?