The Viper 90 and Viper 90R Silver Series ATVs have arrived. The EPA-approved 4-stroke Viper 90/90R's 88.4 cubic centimeter engine allows additional performance and freedom from a youth ATV. The Viper 90 and Viper 90R include necessary equipment to comply with EPA emissions standards. The Viper 90R also features reverse gear functionality for improved mobility.