The jets just have a different flow rate and depending on the specs on different motors you just change the jet to suit , some motors have a larger intake snorkel, straight manifold ,high/ low comp head ,different flow rates in orifices in different LM carbs and primer caps ,more efficient later designed motors will produce more torque with a smaller jet compared with an older motor with larger jet.
2 rings = 39-40m/l per min , 1 ring = 125cc & 85cc 43-45m/l per min, plain face = 160cc & 170cc 45-47m/l per min, 4 ring = 40 - 42m/l per min , I read somewhere that the VSX 160 cc had 25 percent more Torque with the larger intake snorkel and straight carb manifold and the ones I've seen have the 2 ring jet.
