1978 Polaris RXL Service Manual, Page 40Get this manual
COMPONENT FUNCT IONS Con'r.l
Adjust mentsJet Need leFloat evel
FINE TUNIN TH MIKUN CA RBURETOR
Se lec tion he Need le et and the et Needl eA ca rbu retor with piston-type thrott le valve is also call ed variable venturi-ty pe ca rbu re to rIn th is type carburetor, the needle je and the jet need le serve to cont ro proper ai r-fuel mixture rat io during the so-call ed med ium throttle valve pening {between 14 and 4 opening)Whether or no the right siz of th ese pa rt is used gives big bearing on the engi ne perfo rmance at partial loadThe jet needl tapers off at ne end and the clearance between he jet needl and the need le jet increases as he thrott le valve openi ng gets wider The air-fuel ixture rat io is con tro lled the height of "En ring that is inserted in to one of he five slots rovided in he head the jet needleThe va-iation of fuel flow based the height ofEn rin is shown chart to the right