|The Hepolite 5288 High Compression piston|
-SG- Here's a Brico piston ring list - from about 1950 (click this link). And also, scans of piston lists from 1938 (Covmo) 1939 (Hepolite) and the early fifties (Wellworthy).
The UK piston producers, from what I have seen, all fail to give a measurement in their literature from gudgeon pin centre to top of skirt. An irritating omission when, for instance trying to assess whether a piston of the appropriate diameter from another make will fit a Norton! For what it's worth - let me stress, only in my experience - the post war 79mm BSA pistons and the Speedway JAP 80mm pistons have gudgeon pins in the wrong place for Norton use without the drastic action of shortening the barrel!