The youth ATV with a little extra power.The mid-range Viper 70 is the first major step-up for your young rider in the Viper series. The two-stroke Viper 70's 68.0 cubic centimeter engine and the EPA-approved four-stroke Viper 70-4's 69.3 cubic centimeter engine allow additional performance and freedom from a youth ATV. The Viper 70-4 includes necessary equipment to comply with EPA emissions standards. Both models also support the optional tether switch and optional remote stop switch for added safety.