2012 Sportsman 400/500 and EFI Tractor Service Manual 9923412, Page 122Get this manual
CARBURATION AND FUEL SYSTEM CV Carburetor System Function
Carburetor Component Function System Float System (Level Control) Main Components Inlet Pipe, Needle and Seat, Float, Float Pin Main Function Main Affect
Mikuni CV Carb Operation
The constant velocity carburetor incorporates mechanically operated throttle plate and vacuum controlled slide valve (vacuum slide)The venturi cross sectional area in the carburetor bore is increased or decreased automatically by the vacuum slide, which moves according to the amount of negative pressure (less than atmospheric) present in the venturiA diaphragm attached to the top of the vacuum slide is sealed to the slide and to the carburetor body forming two chambersThe chamber above the diaphragm is connected to the venturi area by drilled orifice in the center of the vacuum slideThe chamber below the diaphragm is vented to atmospheric pressure by passage on the air box side of the carburetorA spring, installed in the center of the vacuum slide, dampens the slide movement and assists the return of the slideDiaphragm Low Pressure From Venturi Atmospheric Pressure