2008 Polaris ATV Predator 50, Sportsman Outlaw 90 Service Manual, Page 96Get this manual
FUEL SYSTEM Jet NeedleNeedle Jet (3834 Throttle)
The jet needle and needle jet have the most effect between 38 and 34 throttle openingSome mixture adjustment can be accomplished by changing the location of the "E" clip on the needleMoving the clip down raises the needle in the jet passage and richens the mixtureMoving the clip up lowers the needle in the jet passage and leans the mixtureLetter and number codes are stamped into the needle and the jet indicating sizes and tapers of eachGeneral Carburetor Representation Clip Position (Shown in #3) Throttle Valve Jet Needle Air Jet By-pass Pilot Outlet Air Box Side Engine Side Throttle Valve Pilot Jet Needle Jet Main Jet Air Box Side
Leaner Richer 4
Main System (34 to Full Throttle)
The main system is designed for delivering fuel between low speed and high speed operationThis system is made up of the jet needle, needle jet, and main jetThe main system begins to take effect as soon as there is enough air flow into the carburetor venturi to draw fuel up through the main jet and needle jet assemblyThis system works in conjunction with the needle jet systemDuring low speed driving, there is very little clearance between the jet needle and the needle jet; therefore, very little fuel from the main jet can pass between the jet needle and the needle jetAs the throttle valve opening is increased, the tapered jet needle is raised farther out of the needle jet, allowing greater fuel flowUnder full throttle opening, the cross sectioned area of clearance between the jet needle and the needle jet becomes greater than the cross sectioned area of the main jetThus the main jet is now controlling the amount of fuel flowGeneral Carburetor Representation