I have an Evinrude 40 Lark model year about 1970. It runs beautifully and starts likewise. The problem is that it idles poorly, mainly due to low revs (but a little uneven too). At the front of the engine, under the cover plate, is a spring loaded screw that looks like an idle rev adjustment screw. Beside it is a knob marked lean-fat on the carburator. The problem is that neither seem to have any effect. The spring loaded screw operates a plastic stop (for the timing adjustment?) but the supposedly metallic stop on the inside mysteriously never reaches as far as the plastic stop so adjusting it obviously will have no effect. The lean-fat knob also has no noticeable effect on idling revs. What to do?
