Originally Posted by madman
Cardboard and RTV? Geez! First of all, it might be a good idea to know what the composition and thickness of the original gaskets were. A lot of gaskets are made of pressed cellulose (fiber) but some specialized gaskets have a metal matrix molded in to strengthen them. Then, there's the matter of the thickness of the gasket. two-stroke engines rely on ports in the walls of the cylinders to time their intake and exhaust, using the wrong gasket can upset this timing and result in a loss of power. Too thin, or too thick, it will change the height of the ports in the cylinders.
RTV on gaskets? According to the 3M Company, GM, Ford, Chrysler, and a bunch of other manufacturers, using RTV sealer on gaskets is a huge No-No... RTV (Room Temperature Vulcanizing) sealer is meant to be used in place of a gasket, not with a gasket. True, in some cases RTV is applied to the corners of some gaskets to aid sealing the joints, but you don't smear the whole gasket with it. (For one, it makes the gasket slippery, and it has a tendency to squeeze out) You might get away with it a time or two, but it ain't right.
RTV, used properly, is designed to be applied to two machined, or stamped surfaces, and assembled while it's still "wet". The sealer "skins over" in 8-10 minutes, is usable in an hour and completely cures in 24 hours.
Letting RTV "skin over" will cause it to split like a grape when the parts are assembled....(Yeah, I know, the guys on "HorsepowerTV" do it all of the time...but their writers don't know any better.
Basically it's designed to be applied, and cure in place, bonding to both parts, forming a silicon rubber gasket....
No good deed goes unpunished.