1992 Johnson Evinrude "EN" 40 thru 55 Service Manual, P/N 508143, Page 99Get this manual
1241 5If the adjustment is too rich, note your reference mark 6Repeat Steps thru for each carburetor
and turn the needle 112 revolution clockwiseWait 15 seconds after each adjustment and repeat this procedure until you reach the highest consistent RPM
7To test your adjustment, run the engine near full throttle for three minutesReturn the engine to idle in gearThe eng ine should maintain smooth idle RPM If your test results vary, repeat Steps thru 5If the engine does not respond properly to these adjustments, check the following: Engine temperature linkage adjustments External recirculation system Sufficient exhaust back pressure Pulse equalization hose