Yamaha 8 Cm Owners Manual

 
Maintenance 
36 
EMU28522 
Maintenance chart 
Frequency of maintenance operations may be adjusted according to the operating condi-
tions, but the following table gives general guidelines. Refer to the sections in this chapter for
explanations of each owner-specific action.
NOTE:
 
When operating in salt water, turbid or muddy water, the engine should be flushed with clean 
water after each use.
The “” symbol indicates the check-ups which you may carry out yourself.
The “” symbol indicates work to be...

 
Maintenance 
37 
EMU28931 
Greasing 
Yamaha marine grease (Water resistant grease) 
8 
EMU28952 
Cleaning and adjusting spark plug
WARNING
 
EWM00560  
When removing or installing a spark plug,
be careful not to damage the insulator. A
damaged insulator could allow external
sparks, which could lead to explosion or 
fire. 
The spark plug is an important engine com-
ponent and is easy to inspect. The condition
of the spark plug can indicate something
about the condition of the engine. For exam-
ple, if...

 
Maintenance 
38 
attempt to diagnose any problems yourself.
Instead, take the outboard motor to a
Yamaha dealer. You should periodically re-
move and inspect the spark plug because
heat and deposits will cause the spark plug
to slowly break down and erode. If electrode
erosion becomes excessive, or if carbon and
other deposits are excessive, you should re-
place the spark plug with another of the cor-
rect type.
Before fitting the spark plug, measure the
electrode gap with a wire thickness gauge;...

 
Maintenance 
39 
Checkpoints 
 
Fuel system parts leakage 
 
Fuel line joint leakage 
 
Fuel line cracks or other damage 
 
Fuel connector leakage 
EMU28990 
Checking fuel filter 
Check the fuel filter periodically. The fuel fil-
ter is a one piece, disposable type. If foreign
matter is found in the filter, replace it. For re-
placement of the fuel filter, consult your
Yamaha dealer. 
EMU29041 
Inspecting idling speed
WARNING
 
EWM00451  
 
Do not touch or remove electrical parts
when starting or...

 
Maintenance 
40 
EMU29120 
Exhaust leakage 
Start the engine and check that no exhaust
leaks from the joints between the exhaust
cover, cylinder head, and body cylinder. 
EMU29130 
Water leakage 
Start the engine and check that no water
leaks from the joints between the exhaust
cover, cylinder head, and body cylinder. 
EMU29171 
Checking propeller
WARNING
 
EWM00321  
You could be seriously injured if the en-
gine accidentally starts when you are
near the propeller. 
 
Before inspecting, removing, or...

 
Maintenance 
41 
 
Check the propeller shaft oil seal for dam-
age.
NOTE:
 
If the shear pin equipped: it is designed to
break if the propeller hits a hard underwater
obstacle to help protect the propeller and
drive mechanism. The propeller will then
spin freely on the shaft. If this happens, the 
shear pin must be replaced. 
EMU30660 
Removing the propeller 
EMU29194 
Spline models 
1. Straighten the cotter pin and pull it out
using a pair of pliers.
2. Remove the propeller nut, washer, and
spacer...

 
Maintenance 
42 
stand. You could be severely injured if
the outboard motor falls on you. 
 
Never get under the lower unit while it
is tilted, even when the tilt support lever
or knob is locked. Severe injury could
occur if the outboard motor accidental- 
ly falls. 
1. Tilt the outboard motor so that the gear
oil drain screw is at the lowest point pos-
sible.
2. Place a suitable container under the
gear case.
3. Remove the gear oil drain screw and
gasket.
NOTE:
 
 
If a magnetic gear oil drain screw...

 
Maintenance 
43 
Yamaha dealer. 
 
Keep away from sparks, cigarettes,
flames, or other sources of ignition
when cleaning the fuel tank. 
 
Remove the fuel tank from the boat be-
fore cleaning it. Work only outdoors in
an area with good ventilation. 
 
Wipe up any spilled fuel immediately. 
 
Reassemble the fuel tank carefully. Im-
proper assembly can result in a fuel
leak, which could result in a fire or ex-
plosion hazard. 
 
Dispose of old gasoline according to lo- 
cal regulations. 
1. Empty...

 
Maintenance 
44 
EMU29400 
Coating the boat bottom 
A clean hull improves boat performance. The
boat bottom should be kept as clean of ma-
rine growth as possible. If necessary, the
boat bottom can be coated with an anti-foul-
ing paint approved for your area to inhibit
marine growth.
Do not use anti-fouling paint which includes
copper or graphite. These paints can cause
more rapid engine corrosion.
ZMU01943 

 
45 
Trouble Recovery 
EMU29424 
Troubleshooting 
A problem in the fuel, compression, or igni-
tion systems can cause poor starting, loss of
power, or other problems. This section de-
scribes basic checks and possible remedies,
and covers all Yamaha outboard motors.
Therefore some items may not apply to your
model.
If your outboard motor requires repair, bring
it to your Yamaha dealer.
If the engine trouble warning indicator is
flashing, consult your Yamaha dealer. 
Starter will not operate. 
Q. Is...