1968 Evinrude Ski-Twin, Ski-Twin Electric 33 HP Outboards Service Manual, Page 19Get this manual
Inspect the inlet needle valve for grooves, nicks, scratchesIf any found, replace f10at valve assemblySee Figure 3-11Gum varnish the needle va1ve must removed with Accessory Engine C1eanerDO NOT attempt to alter the shape of the needle va1veCheck the need1e valve seat with magnifying glass; if seat is nicked, scratched, worn out-ofround, it wiH not give satisfactory serviceSee Figure 3-12valve seat and needle matched set; if is worn, both parts must rep1acedUse new gasket when installing the needle seat WORN
Figure 3-13Need1e Va1ve Wear Check gasket surfaces for nicks, scratches, distortionSlight irregu1arities can corrected with the use of surface p1ate and c10thCheck throttle and choke shafts for excessive Check operation of choke and throttle va1ves to sure they correctly shut air f1ow, yet move freely without bindingcarburetor if valves shafts excessively worn damagedNOTE threaded edges of the choke and throttle valve attaching screws staked during carburetor assembly to prevent 10ss during operationDisassembly of these valves is possible, but rep1acement of the carburetor is recommendedd Check hinge pin anchor holes; body if wornPLUGS