Spark Plug Inspection; Carburetor Adjustments; Lubrication Points - Mercury 20 Manual

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MAINTENANCE
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SPARK PLUG INSPECTION AND REPLACEMENT
WARNING
Avoid serious injury or death from fire or explosion caused by damaged
spark plug boots (a). Damaged spark plug boots can emit sparks. Sparks
can ignite fuel vapors under engine cowl. To avoid damaging spark plug
boots, do not use any sharp object or metal tool such as pliers, screwdriv-
er, etc. to remove spark plug boots.
1
Remove the spark plug leads by twisting the rubber boots slightly and pull off.
2
Remove the spark plugs to inspect. Replace spark plug if electrode is worn or
the insulator is rough, cracked, broken, blistered or fouled.
3
Set the spark plug gap. See Specification Chart in General Information Section.
4
Before installing spark plugs, clean away dirt on the spark plug seats. Install
plugs finger tight, and tighten 1/4 turn or torque to 20 lb. ft. (27 N·m).
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CARBURETOR ADJUSTMENTS

Slow Speed Mixture Adjustment
1
Remove access plug from cover.
2
Before starting engine, turn the slow speed mixture screw in until it is lightly
seated then back it out 1-1/2 turns.
3
With the boat tied securely to dock, start engine and allow it to warm up.
4
Shift the outboard to forward gear and reduce engine speed to idle.
5
Turn the slow speed mixture screw slowly in until the engine starts to misfire
or stall due to a lean mixture. Note the position of the screw slot.
6
Turn the slow speed mixture screw slowly out until the engine starts to "load
up" or fire unevenly due to a rich mixture.
7
Set the slow speed mixture screw midway between the rich and lean setting.
When in doubt, set the mixture slightly rich rather than too lean.
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Engine Idle Speed Adjustment
8
With boat tied securely to dock, start engine and allow it to warm up.
9
Shift outboard to forward gear and reduce engine speed to idle. Make sure the
Primer/Fast Idle Knob is pushed all the way in and turned to the slowest idle
speed.
10
Adjust the idle speed screw to obtain the recommended engine idle speed.
(Refer to Specification Chart in General Information Section.)
High Speed Mixture Adjustment
The carburetor is equipped with a standard size high speed fixed jet that is
replaceable for operation at higher elevations.
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LUBRICATION POINTS

Lubricate Points 1 thru 6 with Quicksilver or Mercury Precision Lubricants
2-4-C Marine Lubricant with Teflon or Special Lubricant 101.
1
Steering Friction Adjustment Shaft (Tiller Handle Models) - Lubricate fitting.
2
Swivel Bracket - Lubricate fitting.
3
Transom Clamp Screws - Lubricate threads.
4
Tilt Tube - Lubricate fittings.
5
Lubricate the throttle and shaft cables, moving components and pivot
locations.
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LUBRICATION POINTS (CONTINUED)
WARNING
The end of the steering cable must be fully retracted into the outboard tilt
tube before adding lubricant. Adding lubricant to steering cable when ful-
ly extended could cause steering cable to become hydraulically locked.
An hydraulically locked steering cable will cause loss of steering control,
possibly resulting in serious injury or death.
6
Steering Cable Grease Fitting (If Equipped) - Rotate steering wheel to fully
retract the steering cable end (a) into the outboard tilt tube. Lubricate through
fitting (b).
Lubricate points 7 With Light Weight Oil
7
Steering Link Rod Pivot Points - Lubricate points.
Lubricate Point 8 with Quicksilver or Mercury Precision Lubricants
Anti-Corrosion Grease or 2-4-C Marine Lubricant with Teflon.
8
Propeller Shaft - Refer to Propeller Replacement for removal and installation
of the propeller. Coat the entire propeller shaft with lubricant to prevent the
propeller hub from corroding to the shaft.
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