Usually, two stroke piston rings are located by a pin in the groove in the piston that locates in a step filed into the ends of the ring. This stops the ring from rotating and is positioned so that the ring ends are kept clear of all port openings. Some engines have a series of holes for the port opening instead of one long slot, so the rings do not bulge out into the port.
There is a ton of literature out there on two stroke port design, which is how they got away from the old peaked pistons. There is quite an art to it to ensure the fresh charge does not go straight out the exhaust port.
There is a good primer on it here
http://edj.net/2stroke/BellPerformanceTuning/Bell Chapter 3.pdf
ISTR Maytag made a flat twin two stroke engine too. That would be a nice one to make. Would have two separate crankcase cavities, one for each cylinder, with a seal on the crankshaft in between.
There is a ton of literature out there on two stroke port design, which is how they got away from the old peaked pistons. There is quite an art to it to ensure the fresh charge does not go straight out the exhaust port.
There is a good primer on it here
http://edj.net/2stroke/BellPerformanceTuning/Bell Chapter 3.pdf
ISTR Maytag made a flat twin two stroke engine too. That would be a nice one to make. Would have two separate crankcase cavities, one for each cylinder, with a seal on the crankshaft in between.