1999 Polaris SLH, SLTH, SLX, SLTX, PRO785 Factory Service Manual, Page 128Get this manual
FUEL SYSTEMCARBURETION Mixture Screw SettingsKeihin Mixture Screw AdjustmentTuning
NOTE: Keihin Carburetor Shown Low Speed (Idle) Mixture Screw Idle stop screw must be properly adjusted (location of throttle plates at idlesee page 3.51)The low speed mixture screw is located lowermost on carburetorRemove limiter cap (pull outward)With craft in the water or test tank, adjust idle speed to specifications (see procedure this section)Start engine, let it idle for one minute to normalize engine temperatureRev engine Slightly for 10-20 seconds and return to idleTurn each mixture screw to obtain highest idle RPMTurn each screw out approximately 14 turn from this pointFine tune to achieve best throttle response3CIO
High Speed Mixture Screw
Some models are equipped with high speed mixture adjustment screwsSevere engine damage will result if high speed screws are adjusted too leanSee lean condition troubleshooting in Maintenance Section for more information1The high speed mixture screw is located uppermost on carburetorRemove limiter cap (pull outward) Turn mixture screw in to lean or out to richen mixture as required to achieve dark brown spark plug color when craft is operated at full throttleWhile operating at full throttle, pull lanyard cord lock plate to stop engine Do not allow engine to idle before stopping engineMove craft to shore and inspect spark plug color