Finally my Harley is going so soon I'll have a Speedmaster...
But I don't understand something you write about pilot jets. I don't understand why you're too lean with a 42 and too rich with 45.
The pilot screw permits to partialize the fuel delivery so a 45 with 1,5 turns on the screw is quite similar to a 42 with 3,5 turns.
In fact when with a pilot screw you are obliged to go over 3 turns, it's better to mount the upper sized jet to have a better tuning range under the screew.
Did someone tell you that the pilot screw must be 3,5 turns open?
Forget it, the pilot screw has to be the position right for your engine and setup. So if 3,5 turns is too rich with a 45 pilot, close it till you'll find good low range and idle speed. May be your right setup is 2,5-2,75 turns out with a 45 pilot.
The right setup for a pilot jet size/screew's turns is when you need choke to turn on a cold engine, and can close choke after about 1 mile idleing (on a middle season spring/autumn).
From lot of reading about this Triumph engine I see they are like a few yars ago Ducati's, where there was never the same jet sizes between two different bikes.
