Explanation of Outboard Engine Maintenance Tasks

Anode

Inspect anode.

If worn or damaged - replace.
If dirty - clean with wire brush.

The anode protects the engine from electrolysis when the engine is in the water. The anode does this by sacrificing itself (i.e. the anode suffers the electrolysis and not the engine). If the metal being protected by the anode is left in the water for an extended period of time, the anode will begin to disintegrate. As a general rule, an anode should be replaced with it is 3/4 of its original size.

To work, the anode must be in contact with the engine and water at the same time. Never paint an anode or it will not work. Also, when installing the anode, make sure the surface between the engine and anode is clean. Remove all trace of oil or grease which will isolate the anode.

Having to replace the anode on an MYC engine is extremely rare because the engines are normally kept in the raised position out of the water.

Propeller

Inspect propeller.

If worn, cracked or damaged - replace.

Occasionally, propellers hit submerged logs or other objects and their fins are bent. If this occurs, the engine may vibrate leading to equipment wear. Small bends on the find can be straighten with a tool or filed down.

Bolts & Nuts

Inspect engine mounting bolts.

If loose - tighten.

This is an important thing to check, especially on an engine after its first season of use. However, it is extremely rare that any of the engine mounting bolts would have to be retightened.

Greasing Points

Apply water resistant grease to the 5 greasing points.

Engine steering bracket. After greasing, swivel engine a few times.
Motor mount clamps. After greasing, work clamps in and out a few times.
Throttle cable where cable comes out of jacket inside engine. Apply only a small amount of grease and work throttle to distribute grease.
Throttle cable where cable comes out under tiller arm. Apply only a small amount of grease and work throttle to distribute grease.
Hood latch. After greasing, operate latch a few times.

After applying grease, always wipe any extra up with rag.

Steering Friction Adjustment

Lubricate screw with WD40
Loosen and tighten steering friction adjustment screw until it operates smoothly.
Tighten screw to get proper friction so engine holds its position when tiller arm is not being held.

It is important to use WD40 and first loosen and then tighten several times the friction adjustment wing nut to work out any corrosion so that it remains adjustable for the life of the engine.

Throttle Friction Adjustment

Lubricate screw with WD40
Loosen and tighten throttle friction adjustment screw until it operates smoothly.
Tighten screw to get proper friction so throttle holds its position when throttle is released.

Fuel Line & Strainer

Inspect fuel line for cracks, leaks or damage. If any, replace.
Inspect fuel strainer. If cracks, leaks or clogged, replace. (The direction mark shows the flow of fuel and should be installed pointing to the carburetor).
Inspect fuel joint for tightness. If loose, tighten bolt beneath.

Spark Plug

Always use correct tool to remove and install spark plugs. Failure to use proper tool can result in unseen damage to spark plug which results in malfunction.

1. Remove spark plug & inspect insulator color.

Medium to light tan color indicates normal condition.
White color indicates lean fuel mixture (plugged filter, jet, air leak or wrong setting).
Blackish color indicates (excess oil used, electrical malfunction or defective spark plug).

2. Replace plug with NGK B7HS-10

First measure & adjust spark plug gap to 0.9-1.0 mm or 0.035-0.039 in.
Clean gasket surface and plug surface.
Apply thin film of anti-seize compound to spark plug threads.
Tighten spark plug to 25 Nm (2.5 m.kg or 18 ft.lb). If torque wrench is not available when you are hand installing a spark plug, a good estimate of the correct torque is 1/4 to 1/2 turns past finger tight,

Start-in-Gear Protection

Check start-in-gear protection.

Put engine in forward gear and attempt to pull starter cord.
If cord does not pull out, protection is correct.
If cord pulls out, protection needs to be adjusted.

To adjust protection:

Shift lever to neutral.
Adjust start-in-gear protection wire. Turn adjusting nut so that the end of the stop plunger aligns with the center of the hole in the starter case.
Tighten the locknut.

Rinse Cooling System

Run fresh water through cooling system to remove salt residue.

Put bottom of engine in tub of clean water.
Start engine and allow to warm up (3 minutes).
Once engine is warm, thermostat will open and flush entire engine with fresh water.
After engine is warm, continue next step of checking idle speed.

Idle Speed

Measure idle speed.

With engine running, attach tachometer to spark plug lead.
Reduce throttle to lowest setting.
Idle speed should be 900 rpm (plus or minus 50 rpm)

Adjust idle speed if necessary.

Turn off engine.
Turn the pilot screw until it is lightly seated (all the way in).
Then turn the pilot screw outward 1 1/8 turns ( plus or minus 1/4 turns).
Start engine & monitor idle speed.
Turn the throttle stop screw in or out until the correct idle speed is obtained. Turning in increases idle speed. Turning out decreases idle speed.

After adjusting the engine idle speed, the throttle control link should also be adjusted.

Ignition Timing

Refer to Yamaha Marine Outboards Service Manual, beginning on page 3-14.

Throttle Control Link

Before adjusting the throttle control link, the ignition timing should be adjusted.

Check full open position.

With engine off, set the shift lever to forward position.
Fully advance the throttle grip.
Check the magneto base stopper so that it contacts with the stopper plate.
Check that the throttle valve is fully-opened.

Adjust if necessary.

Remove the joint link.
Set the shift lever to forward position.
Bring the stopper on the full-advanced side of the magneto base to contact the magneto base stopper.
Fully open the throttle.
Adjust the cable on the "pull" throttle cable until to fully-open the carburetor throttle valve.
Tighten the lock nut on the "pull" throttle cable.
Adjust the cable adjuster on the "push" throttle cable until there is 3 mm (0.12in) of free play in the throttle grip.
Tighten the lock nuts.
Adjust the length of the joint link so that the control lever comes to contact with the magneto base.
Connect the joint link.
Check the throttle valve to fully open position

Motor Body & Cover

Check Outboard Motor Body

Tilt pin, inspect/clean/replace
Test tilt operation
Spot prime and paint any spots of bare metal.

Outboard cover

Test cover latch & adjust if necessary
Repair cracks as necessary with fiberglass & thickened expoy.
Spot prime and paint as necessary.