hmm the cases are metal to metal, so is many other things, probably why they use sealant to makes sure nothing leaks out. hence the use of ultra gray or yamabond, etc
if a guy puts a 4mm crank and a plate with no porting then he deserves for it to run like ass. why even dick with it if your not going to do it correctly.
and the plate motors i put together and seen usually the ones of jims, you put the bottom end together, spread ultra gray, yamabond, whatever, plate, spread ultra gray on top of the plate, then spread some on the bottom of the jugs with your fingers lightly, put jugs on the studs and torque down, let it setup, its basically completely seals up the whole thing, if it leaks its because you didnt put the ultra gray down correctly. like caulking your houses basically just seals up motors.