2003 Polaris Scrambler 50-90 Sportsman 90 Predator 90 Service Manual, Page 61Get this manual
FUEL SYSTEMCARBURETION inside the needle jet
THROTTLE SLIDE
The throttle slide controls the rate of engine air intake by moving up and down inside the main boreAt small throttle openings, air flow control is performed chiefly by the cutawayBy controlling air flow the negative pressure over the needle jet is regulated, in turn varying the fuel flowThrottle Valve
Needle Jet
Main Jet Engine Side Air Box Side
THROTTLE OPENING VSFUEL FLOW
In full throttle condition the cross sectioned area between the jet needle and the needle jet is larger than the cross sectioned area of the main jetThe main jet therefore has greater control over fuel flowSmall Clearance Medium Clearance Large Clearance
Cutaway Higher cutaway numberleaner mixture The throttle valves are numbered 1.0, 1.5, 2.0, etc according to the size of the cutawayThe higher the number, the leaner the gasolineair mixture