Mercury 4 SERIES

CARBURETOR
Page 3B-6 90-857138R1 MAY 2000
Carburetor Adjustments
Idle Speed - Initial Setting
Pilot (Idle Mixture) Screw
1. Turn pilot mixture screw in (clockwise) until lightly seated than back out to an initial set-
ting of 3 ± 1/2 turns.
2. Start engine and run at slow/idle speed in forward gear. Turn pilot screw in until engine
starts to lose rpm, than back out 1/4 turn and adjust for best performance.
NOTE: Allow time for engine to stabilize between adjustments. DO NOT adjust leaner than
necessary to attain reasonably smooth idle.
If the engine hesitates on acceleration, readjust the pilot screw.
a
a-Pilot Mixture Screw
Idle Speed
1. Adjustment:
• Tightening the screw increases engine speed.
• Loosening the screw reduces engine speed.
Idle RPM
1300 rpm Out of Gear
1100 rpm in Gear
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a
a-Idle Adjustment Screw