1971-1973 Arctic Cat Snowmobiles Factory Service Manual, Page 92Get this manual
CARBURETION (TILLOTSON) air flow velocity by utilizing throttle valve will govern the amount of fuel delivered to the enginesecondary idle discharge ports, as well as the main fuel discharge portAt this time, low pressure area is formed on the fuel side of the main diaphragmAtmospheric air pressure on the reverse side of the main diaphragm will force the main diaphragm upward, causing the diaphragm button to depress the inlet control lever, overcoming the inlet tension spring pressureFuel will now enter through the inlet seat by forcing the inlet needle off its seat contact, into the fuel chamber side of the main diaphragm, through the idle and main fuel supply orifices and channels, and out the discharge ports to the engine
Starting Operation (Choke)