2001 Polaris SLH, Virage PWC Factory Service Manual, Page 147Get this manual
CarburetionExhaust Mixture Screw Adjustment and Tuning
1The low speed mixture screw is located lowermost on carburetorRemove limiter cap (pull outward) 2With 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 idle4Turn each mi xture screw to obtain highest idle RPM 5Turn each screw out approximately 14 turn from this pointFine tune to achieve best throttle response
Fuel Tank Vent Operation
The fuel tank vent system consists of an inlet check valve and pressure relief valveThe inlet check valve allows air to enter the tank as the fuel supply is being used The pressure relief valve maintains 1-1.5 PSI positive pressure in the fuel tankIf pressure in the tank exceeds 1.5 PSI, the valve releases and excess pressure is allowed to escape
Inspection
The check valves can be tested for proper operation by applying pressure to one end with the Mity Vac 1MApply approximately PSI to the end of the valve marked VACThe valve should hold steady pressureTry to apply pressure to the other end of the valve, it should allow air to go through easily with no pressure build upReplace the check valve if found to be faulty