Quote Originally Posted by WebleyWombler View Post
Good advice from an expert!
I have a couple of FLZ gems with the stacked discs and what I have done is carefully ground the end of the riveted stub and removed the steel and leather washer stack. I then fitted the cup washer from a primus stove pump with a leather tap washer to reinforce the centre. then fitted a steel washer and re riveted the piston. All works ok
Sounds like a good plan if the steel on the piston stub is workable/ can be peened over again. Sometimes the steel used in some gem pistons is extremely hard and difficult to drill/machine (possibly case hardened?) if memory serves, that is usually the machine fit piston types though.