2012 Sportsman 400/500 and EFI Tractor Service Manual 9923412, Page 126Get this manual

2012 Sportsman 400/500 and EFI Tractor Service Manual 9923412, Page 126

CARBURATION AND FUEL SYSTEM AirFuel Mixture Ratio E-Clip Position vsFuel Flow 4 Jet Needle The jet needle has five adjustment
venturi type carburetorIn this type of carburetor, the needle jet and jet needle serve to control proper airfuel mixture
ratio at the medium throttle valve opening (between 14 and 34 opening)Having the proper needle jet and jet needle has major
impact on engine performance at partial loadThe jet needle tapers off at one end and the clearance between the jet needle
and the needle jet increases as the throttle valve opening gets widerThe airfuel mixture ratio is controlled by the height
of the "E" clip inserted into one of the five slots provided in the head of the jet needleThe previous chart shows the variation
of fuel flow based on the height of the "E" clip Needle Jet The needle jet works in conjunction with the jet needle to regulate
fuel flow rateAn air bleed opening in the side of the needle jet brings in air measured by the air jetThis air initiates
the mixing and atomizing process inside the needle jetNeedle Jet Main Jet 99234122012 Sportsman 400500 and EFI Tractor Service