Most two stroke engines are designed to rotate in one direction by the location and heights of the ports. Two strokes that are designed to run in both directions have the locations and port heights designed to do so. You may find you cannot simply move the ignition and expect the engine to rotate in the opposite direction with the same power. Some success at getting an engine to counter rotate by rotating the cylinder 180 degrees. Some nitro motors had both front bearing/crankshaft housing and back plate bolted on to the crankcase with the same bolt pattern and you could end up with a counter rotating motor by switching these end around. The piston relative to the cylinder still rotated in the same direction but the crankshaft being on the back of the engine gave it the opposite direction of rotation. Enya 4 strokes were reversible by swapping the intake and exhaust cams then spinning the cylinder, head, piston and rod 180 degrees on the crankcase.

Dennis