First, check again when you have more miles on the bike. Triumphs are just getting run in good at about the same mileage that imports from the other direction are all used up.
As was mentioned, the carbs could be out of sync or just in need of adjusting.
It would also probably help to change to a less restrictive exhaust system and pop out the rubber bits in the airbox. The more power the engine expends sucking in air and forcing it back out again, the more gas it eats.
One of the tricks that Chrysler used in the old Mobilgas economy runs was to get through the gears as quickly as possible. As soon as the bike will pull well enough in the next gear up, shift.
I don't know how many miles to the gallon I would have gotten with my bike stock because I started changing things as soon as I got home but, as it is now, I usually get mid to upper 40's. Best ever was 53. And, that is statute miles per US gallon.
