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 Ring – 622/502-15 (Equivalent to 20 Pilot Jet in pre-Premier carbs.)
2 Rings – 622/502-17 (Equivalent to 25 Pilot Jet in pre-Premier carbs.)
3 Rings – 622/502-19 (Equivalent to 30 Pilot Jet in pre-Premier carbs.)
4 Rings – 622/502-21 (Equivalent to 35 Pilot Jet in pre-Premier carbs.)
5 Rings – 622/502-23 (Equivalent to 40 Pilot Jet in pre-Premier carbs.)
OEM: 622/502-15, 622/502-17, 622/502-19, 622/502-21, 622/502-23
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