1973 Evinrude Norseman 40 HP Service Manual, Page 20Get this manual
bInspect the inlet needle valve for grooves, nicks, or scratchesIf any are found, replace float valve assemblySee Figure 3-11Gum or varnish on the needle valve must be removed with OMC Accessory Engine CleanerDO NOT attempt to alter the shape of the needle valvecCheck the needle valve seat with magnifying glass; if seat is nicked, scratched, or worn out-ofround, it will not give satisfactory serviceSee Figure 3-12The valve seat and needle are matched set; if either is worn, both parts must be replacedUse new gasket when installing the needle seat WOH.N)'
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Figure 3-13Needle Valve Wear Check all gasket surfaces for nicks, scratchesor distortionSlight irregularities can be corrected with the use of surface plate and emery loth cCheck throttle and choke shafts for excessive play Check operation of choke and throttle valves to be sure they correctly shut off air flowyet move freely without bindingReplace carburetor body if valves or shafts re excessively worn or da maged
Figure 3-11Inlet Needle Valve Wear