Thanks all for the help. It turns out it is simple to do. The carbs have the correct hole already in the side and it goes almost all the way down to the pilot air passage.
All you have to do is with a tiny drill (like #57) poke through the last mm or so.
If you remove the pilot screw you can see daylight right through.
The port is 6mm for the hose but steps up to 7mm for the press fit into the hole.
Some locktite will probably help.
Got some on order from Hermy¡¯s senior (610 562 3155), not the son who runs the BMW/Triumph dealer.
Richard Chawes
