Triumph Repair: TR6 Carburettor, damper, oil

Question
What type of fluid do you put in the carbs

Answer
If it is the stock CD-175, a lightweight oil.

Some have used auto transmission fluid, and some heavier weight motor oil (30w)

It all depends on how fast you want the piston to move/react to throttle changes.  Racers don't put any oil so that they get instant reaction, at the expense of the piston not have any smooth transition.