Did Scotts ever have a tube joining the two halves of a saddle tank? The point of this is to give access to the petrol in the right hand lobe. There may have been another tap fitted on the right hand side to act as a reserve. Derek Swetnam
If my old Vincent Comet is anything to go by two taps will probably be almost unnecessary, the fuel will quite happily crawl over the “hump”, (the Vincent’s 3 1/2 gallon tank sits astride the top frame/oil tank member), to such effect that I use it as a “reserve”. By running on one tap until the petrol runs out on that side and then turning on the other I had a handy 15 miles or so left on a machine that would return 75mpg all day. So there we are, fit two taps, use one and you have a reserve! And by the way Stevenage used to advertise the Comet as “The vibrationless single” so while it may not be as smooth as a good Scott it is not some sort of “eyeballs going around like a fruit machine” job either!
Given the vibration from a Vincent, I can quite understand how the petrol would migrate over the hump in the tank – but not on a super-smooth Scott.
The two outlets from the tank were intended to couple together externally so one pipe fed the carb, hence you had a “reserve” by using just one tap, and turned the other one on when the first “side” ran out.