1971-1973 Arctic Cat Snowmobiles Factory Service Manual, Page 91Get this manual
CARBURETION (TILLOTSON) General
The Tillotson carburetor incorporates diaphragm controlled metering system which allows precise fuel metering to the engine at extreme angles and vibration factors prevalent during snowmobile operationThe proportionate amount of fuel passing through the carburetor metering chamber is always equal to the fuel demanded by the engine during operationThe dual venturi multiplies the venturi pressure drop, causing extremely fine atomization of the fuel that is delivered by the main fuel nozzleAs result, fuel reaches the engine as combustible fog rather than fluid streamhigh and low, the fuel velocity increasesVelocity is then defined as the distance fuel can be raisedVENTURI venturi is restricted area where air is allowed to pass throughBecause of the venturi design, pressure varies between the inside of the carburetor throat and the outside airThis is to allow better atomization of the fuel in the carburetor, resulting in better engine performance at all operating speedsWhen air moves through the venturi, the velocity of air flow is increased due to the restriction of the venturi areaNOTE: The venturi produces vacuum at the point of maximum restriction