they r all about tha same. On the Tomos Tomos, Tomos lx , and the Revival, you do not need to pre-mix oil since it has oil injection- the tank for gasoline, and an under-the-seat oil tank. But with the sprint , you do need to premix oil. The lightest is the Tomos Sprint, and it is also the cheapest, but it doesnt have oil injection. if you would wana build the fastest , i would go for the tomos tomos, since its lighter than the tomos lx and the revival but it has oil injection. but its up to u. but the reviival is a heavy bike, i would go for that