2008 Polaris ATV Predator 50, Sportsman Outlaw 90 Service Manual, Page 93Get this manual
FUEL SYSTEM AirFuel Mixture Ratio
E-Clip Position vsFuel Flow 4
Jet Needle
The jet needle has five adjustment grooves cut into the upper portion, and is tapered from approximately the middle of the needle to the lower endThe top is fixed to the center of the throttle valve by the needle clip, and the tapered end extends into the needle jetFuel flows through the space between the needle jet and jet needleThis space does not vary until the throttle reaches the 14 open pointAt that time the tapered portion of the needle begins to move out of the jet, affecting fuel flow as the opening enlargesIf the needle clip is changed from the standard position to lower groove, the needle taper starts coming out of the jet sooner, resulting in richer mixtureMoving the clip higher produces leaner mixtureIf the taper is worn due to vibration, fuel flow may be significantly affectedJet Needle Leaner Position# Richer
75 Throttle Valve Opening