@blacklav sorry if I’m asking you a stupid question.
You are referring only to the hole at the end of the pilot jet?
That’s the only one that is precisely drilled - the holes in the side are not metered at all.
I think I have put this up here before, but it’s a useful reference.
Here is a mail received from Amal sometime ago when we were trying to troubleshoot the Dommie:
The brass headed screw in the position opposite to the Pilot Air Screw is the new design of pilot jet which replaces the pilot bush.
It is identifiable by the crossed slots in the head.
The attached photo shows it in position.
The jet is is intended to be screwed firmly into the carburetter.
The method of adjusting the idle is unchanged from the standard Mark 1.
(The Standard (non–Premier) carburetters now have a plated threaded plug with a single slot screwed into the same position to improve access to the bush for cleaning.)
The ID of the standard jet is 0.017”
This is the same as the nominal ID of the former pilot bush which was rated at approximately 23cc.
The new jets are also available in 15, 19, 21 and 23 sizes which again are measured in thousandths of an inch.
The graduations between the jets are smaller than the 124/026 range of pilot jets, one jet size being equivalent to approximately ¾ of a turn on the Pilot Air Screw.
The most popular alternative size so far is the 19.
Identification is by rings engraved around the nose of the jet, as listed below.
Premier ID Grooves
1 - 622/502-15
2 - 622/502-17
3 - 622/502-19
4 - 622/502-21
5 - 622/502-23