This is a high quality treated carburetor with perfect behavior at idle and acceleration. Easy to install and turns on instantly. Please make sure the fuel is pure enough before installation. You need to adjust the carburetor a little after installation because each scooter bag engine condition is different from ATV. Thank you. Fitment: This is an aftermarket carburetor replacement for all 47cc 49cc 2 stroke mini ATV quads. This is a replacement part Aftermarket carburetor replacement with optimized combination and good packaging, easy to install in place of the original carburetor. Higher quality and greater durability Each carburetor is thoroughly tested and the idle speed and acceleration performance of the carburetor are guaranteed. The original carburetor is directly adjustable, easy to adjust, fill and ready to run in your locomotive deserves a powerful carburetor. There is no instructions on how to replace the carburetor, but you can search on the Internet, it's easy to find, thanks