......we have keep changing pistons about as often as we change our underware.  Some guys go longer between changes.

And that just depends on who did your motor work, needless to say I always bring at least 2 extra pairs!!!


On a more serious note, I have a full JH built motor and pipe and I usually get 30-35 hours out of a piston.  When I pull it it's usually got a crack in it, sometimes pretty small though.