1979 Evinrude 4 HP Outboards Service Manual, PN 5424, Page 23Get this manual
CLEANING, INSPECTION AND REPAIR GENERAL INSTRUCTIONS Clean all parts, except cork float, in solvent and blow dryDO NOT dry parts with cloth as lint may cause trouble in the reassembled carburetorBe sure all particles of gaskets are removed from gasket surfacesFlush out passages in the carburetor body and float chamber with solvent and remove any gummy deposits with OMC Engine CleanerCertain solvents will not remove this gum which accumulates particularly in the float chamber and on the needle valves
Figure 3-10Inlet Needle Valve Seat Wear
FLOAT AND NEEDLE VALVE aI nspect float and arm for wear or damageIf the cork float has become oil-soaked, discard it and install new oneCheck float arm wear in the hinge pin and needle valve contact areas, and replace if necessarybInspect hinge pin for wear, which may result from excessive vibrationReplace if necessarycInspect the float needle valve for grooves, nicks, or scratches; if any are found replace float valve assemblySee Ffgure 3-9Gum or varnish on the needle valve may be removed with OMC Engine CleanerDO NOT attempt to alter the shape of the needle valve or sealdCheck the needle valve seat with magnifying glass; if seat is nicked, scratched, or worn out-of-round, it will not give satisfactory serviceThe valve seat and needle are matched set; if either is worn, both parts must be replacedUse new gasket when reinstalling the needle seatSee Figure 3-10NEEDLE VALVES aInspect the tapered end of the needle valves for grooves, nicks, or scratches; replace if necessarySee Figure 3-11 bDO NOT attempt to alter the shape of the needle valves