The rings have nothing to do with holding the piston away from the cylinder. The rings hold compression from getting into the crankcase. The oil keeps parts from touching. There are a lot of two strokes that only have one ring, I have one of the happy time engines that I have with only one ring on the piston, it is more for racing but it is OK for these. The wide double rings on these engines indicates a simple durable engine. You can install the piston in the barrel first leaving just enough out the bottom to slip the pin in, make sure the clip is in the slot to hold the pin in. Have fun, Dave