Complex sentence: Although there are several variant models of the SR50 worldwide, certain models are not available in certain parts of the world: the carburetor model was available just on a few models in the first few years of the SR50 since being introduced to North America.
Split into simpler sentences: Although there are several variant models of the SR50 worldwide, certain models are not available in certain parts of the world. The carburator model was available just on a few model in the first few years of the SR50 since being introduced to North America.