My BB Gold Star came to me with a well sorted Concentric but, while on one hand I should leave well enough alone, on the other hand it would look better with the TT it had come with from the factory. Although I have two TTs of the correct size, and have collected information about these carburetors from every source I could locate, for now 'well-enough' has the upper hand so they sit on the shelf. However, my recent acquisition of a 1928 Ariel for next year's Cannonball cross country rally has me thinking of the TT again.
In their contemporary TT literature Amal pointed out that greatest power at full throttle wasn't the only concern in racing because "there are 'Governor's Bridges', and also that you have to 'get up' to full bore." The TT's needle has seven grooves and slides were originally supplied with six cutaways, allowing fine steps in tuning the carburetor. Presumably, these fine steps mean it would be possible to get the jetting closer to "perfect" over the entire range than can be achieved with a Type 6, Monobloc or Concentric. "Perfect" jetting over the full range would result in the highest possible fuel economy which is important to me on a bike whose tank only holds 2.4 U.S. gallons of fuel and where ~250 miles/day will be covered.
Note that a Mikuni on the Ariel isn't an option because of regulations, and a Mikuni on a Gold Star isn't because of aesthetics.
So, those of you who have lots of practical experience with TTs, can they be tuned to work better over their entire range of throttle positions than any of the "conventional" Amals? Even if this is the case, are they more sensitive to atmospheric conditions than conventional Amals? That is, if the jetting is perfect at 72 oF at sea level, will a TT be further away from perfection when it is at, say, 85oF and 2500 ft. than a conventional Amal would be?