Greetings All, Was wondering if any of you might be able to settle an argument for me? A friend and I have been debating the subject of the CB1300's pistons, namely their being described as "semi-forged"- my friend seems to think no such beast exists, that pistons can only be forged or cast. As a welder i know a fair bit about various hardening treatments, but mainly in relation to steel, so felt rather disadvantaged in the discussion with my friend who is a qualified motorcycle mechanic (gained his trade in barely over 2 years then left the industry but thats another story!). My thinking is that, by "semi-forged" they mean the piston is essentially cast, then the crown heated and compressed, to perhaps get the benefits of forging at less cost? Meanwhile, old Ralphy is insisting that doing this to a piston would create too many stress fractures and would only serve to weaken the piston. Sorry for the rather obscure question, but can any mechanics/metalurgists/smart people shed any light on what this process might involve and/or benefits?