So what is the purpose of having a NS and a MT version of the engine. Since both have same piston and sleeve set. The stroke is still 14mm.
The factor that change the stroke value is the distance between the center of crankpin to the center of the crakshaft, which equals 1/2 stroke. So a 14mm stroke will have the center of crankpin to center of crankshaft of 7mm. one complete revolution will move the conrod up and down 14mm. Am I right.

So in order for the new long stroke engine to have longer stroke, the distance bw crankpin center to crankshaft center must be change although the conrod may remain the same length!!