from what I am learning, what once was the most popular engine in the world, the horizontal 90cc engine grew to 110cc, then 125cc, now 140cc, and a dozen or more configuration packages kick start, electric start, semi-automatic, standard, with reverse, universal for pit bikes atvs, with belt drive for scooters. The 190cc is more of a race motor, I'm leaning toward the 190, mostly, cause it is a 5spd, and conventional 1down, 4up pattern, I think the 140 has sufficient power to satisfy my wants, I don't care if I struggle to go much faster than 60, the 125 stock motor struggles to do 50 with my body mass, but being able to go 75 won't scare me