I never knew that BSA pistons needed to be fitted with a gudgeon pin marked with the same colour code as the piston. No colour code on this pin so not sure what piston to use it for. I do seem to remember having seen pistons with some yellow paint on it.
Henk
email (option): ahum@quicknet.nl
Interesting..another example of 'selective' assembly to accomodate manufacturing tolerances. I have never seen this instruction before..and have not found it in the many boxed, sealed, NOS BSA pistons I have had (either 'civvy' or 'WD').
Did this come with a BSA or aftermarket piston? Looking at the label I guess a BSA one.
WD instruction B124 details instructions for the fitting of Hepolite pistons so it is apparent not only BSA pistons were used.
The tolerances for the pin and piston pin bores are fairly tight, with the pin finish ground to .7500"-.7502" and the pin bores to .7500"-.7497"...These sizes produce an intereference fit for the pin even with the smallest pin dimension and the largest pin bore dimension but maybe it was felt a 'size for size' interference fit was not sufficient. Alternatively, perhaps pistons and pins of an earlier manufacture date were not so tightly toleranced....Ian