Engine Idle Speed Adjustment - Mercury 20 Manual

6. Turn the slow speed mixture screw slowly out until the engine starts to load up or fire unevenly due to a
rich mixture. Note the position of the screw slot.
7. Set the slow speed mixture screw midway between the rich and lean setting. When in doubt, set the
mixture slightly rich rather that too lean.

ENGINE IDLE SPEED ADJUSTMENT

1. With boat tied securely to dock, start engine and allow it to warm up.
2. Shift the outboard to forward gear and reduce engine speed to idle. Ensure the primer/fast idle knob is
pushed all the way in and turned to the slowest idle speed.
3. Adjust the idle speed screw to obtain the recommended engine idle speed. Refer to General Information ‑
Specification.
HIGH SPEED MIXTURE ADJUSTMENT
The carburetor is equipped with a standard size high speed fixed jet that is replaceable for operation at higher
elevations.
MAINTENANCE
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