4-stroke spraying machine, also known as a 4-stroke motorized knapsack sprayer or power sprayer, is a motorized device for applying liquids like pesticides, fertilizers, or disinfectants to large areas. It is powered by a 4-stroke engine, which provides consistent power for efficient and uniform spraying without manual pumping, leading to reduced labor and improved coverage compared to hand-pump models. Key features include a 4-stroke engine for better fuel efficiency and quieter operation, a comfortable knapsack design for portability, and durable construction for harsh conditions.