Saitos have a "jug," a 1-piece cylinder and head just like all the small industrial 2-strokes, weed eaters, chain saws, etc. Some of the earlier ones had a brass sleeve inside, but all the newer ones use the chrome plated bore. This is the reason they are the lightest weight of any of the 4-strokes.

As for fuel, check what the guys at Horizon use and it's mostly 30% heli fuel. In tests, Saitos tend to gain considerable rpm from a higher nitro content, whereas OS 4-strokes gain very little. I tend to run regular 10% Omega, castor blend fuel in mine.