1997 Johnson Evinrude "EU" 40 thru 55 2-Cylinder Service Manual, P/N 507265, Page 97Get this manual
5If the adjustment is too rich, note your reference mark and turn the needle Va revolution clockwiseWait 15 seconds after each adjustment and repeat this procedure until you reach the highest consistent RPM
6Repeat Steps thru for each carburetor7To test your adjustment, run the engine near full throttle for three minutesReturn the engine to idle in gearThe engine 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 followi ng: Engine temperature Linkage adjustments External recirculation system Sufficient exhaust back pressure Intake manifold balance passage