Yamaha C40 Manual

							 
Operation 
36 
EMU27881 
Adjusting trim angle 
Power trim and tilt models
WARNING
 
EWM00750  
 
Be sure all people are clear of the out-
board motor when adjusting the tilt an-
gle, also be careful not to pinch any
body parts between the drive unit and
clamp bracket. 
 
Use caution when trying a trim position
for the first time. Increase speed gradu-
ally and watch for any signs of instabil-
ity or control problems. Improper trim
angle can cause loss of control. 
 
Use the power tilt switch located on the
bottom engine cowling (if equipped)
only when the boat is at a complete 
stop with the engine off. 
Adjust the outboard motor trim angle using
the power trim and tilt switch.
To raise the bow (trim-out), press the switch
“” (up).
To lower the bow (trim-in), press the switch 
1. Trim operating angle
ZMU031091
 
1. Power trim and tilt switch
1. Power trim and tilt switch
1. Power trim and tilt switch
UP
DN
ZMU03110
1
DOWNUP
ZMU03096
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Operation 
37 
“” (down).
Make test runs with the trim set to different
angles to find the position that works best for
your boat and operating conditions.
NOTE:
 
To adjust the trim angle while the boat is
moving, use the power trim and tilt switch lo-
cated on the remote control device or tiller 
handle, if equipped. 
EMU27911 
Adjusting boat trim 
When the boat is on plane, a bow-up attitude
results in less drag, greater stability and effi-
ciency. This is generally when the keel line of
the boat is up about 3 to 5 degrees. With the
bow up, the boat may have a greater tenden-
cy to steer to one side or the other. Compen-
sate for this as you steer. The trim tab can
also be adjusted to help offset this effect.
When the bow of the boat is down, it is easier
to accelerate from a standing start onto
plane. 
Bow Up 
Too much trim-out puts the bow of the boat
too high in the water. Performance and econ-
omy are decreased because the hull of the
boat is pushing the water and there is more
air drag. Excessive trim-out can also cause
the propeller to ventilate, which reduces per-
formance further, and the boat may “por-
poise” (hop in the water), which could throwthe operator and passengers overboard. 
Bow Down 
Too much trim-in causes the boat to “plow”
through the water, decreasing fuel economy
and making it hard to increase speed. Oper-
ating with excessive trim-in at higher speeds
also makes the boat unstable. Resistance at
the bow is greatly increased, heightening the
danger of “bow steering” and making opera-
tion difficult and dangerous.
NOTE:
 
Depending on the type of boat, the outboard
motor trim angle may have little effect on the 
trim of the boat when operating. 
EMU27933 
Tilting up and down 
If the engine will be stopped for some time or
if the boat is moored in shallows, the out-
board motor should be tilted up to protect the
propeller and casing from damage by colli-✩✦✯✬✤✲✲✣ ✦✪ 	
 


 
						

							 
Operation 
38 
sion with obstructions, and also to reduce
salt corrosion.
WARNING
 
EWM00220  
Be sure all people are clear of the out-
board motor when tilting up and down,
also be careful not to pinch any body
parts between the drive unit and engine 
bracket.
WARNING
 
EWM00250  
Leaking fuel is a fire hazard. If there is a
fuel joint on the outboard motor, discon-
nect the fuel line or close the fuel cock if
the engine will be tilted for more than a 
few minutes. Otherwise fuel may leak.
CAUTION:
 
ECM00241  
 
Before tilting the outboard motor, stop
the engine by following the procedure
on page 34. Never tilt the outboard mo-
tor while the engine is running. Severe
damage from overheating can result. 
 
Do not tilt up the engine by pushing the
tiller handle (if equipped) because this 
could break the handle. 
EMU28005 
Procedure for tilting up 
Power trim and tilt models / power tilt models
1. Place the remote control lever / the gear
shift lever in neutral.2. Disconnect the fuel line from the out-
board motor or close the fuel cock.
3. Press the power trim and tilt switch /
power tilt switch “” (up) until the out-
board motor has tilted up completely.
ZMU03108
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Operation 
39 
4. Push the tilt support knob into the clamp
bracket or pull the tilt support lever to-
ward you to support the engine.
WARNING
 
EWM00260  
After tilting the outboard motor, be sure
to support it with the tilt support knob or
tilt support lever. Otherwise the outboard
motor could fall back down suddenly if oil
in the power trim and tilt unit loses pres- 
sure. 
5. Models equipped with trim rods: Once
the outboard motor is supported with the
tilt support lever, press the power trim
and tilt switch “” (down) to retract the
trim rods.
CAUTION:
 
ECM00250  
Be sure to retract the trim rods complete-
ly during mooring. This protects the rods
from marine growth and corrosion which
could damage the power trim and tilt 
mechanism. 
EMU28053 
Procedure for tilting down 
Power trim and tilt models / power tilt models
1. Push the power tilt / power trim and tilt
switch “” (up) until the outboard motor
is supported by the tilt rod and the tilt
support lever / tilt support knob becomes
free.
2. Release the tilt support lever or pull out
the tilt support knob.
UP
ZMU01935
UPDN
UP
ZMU04993
ZMU03115
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Operation 
40 
3. Push the power tilt / power trim and tilt
switch “” (down) to lower the outboard
motor to the desired position. 
EMU28060 
Cruising in shallow water 
The outboard motor can be tilted up partially
to allow operation in shallow water. 
EMU28090 
Power trim and tilt models / power tilt 
models 
The outboard motor can be tilted up partially
to allow operation in shallow water.
WARNING
 
EWM00660  
 
Place the gear shift in neutral before
setting up for shallow water cruising. 
 
Return the outboard motor to its normal
position as soon as the boat is back in 
deeper water.
CAUTION:
 
ECM00260  
Do not tilt the outboard motor up so that
the cooling water inlet on the lower unit is
above the surface of the water when set-
ting up for and cruising in shallow water.
Otherwise severe damage from overheat- 
ing can result. 
EMU28184 
Procedure for power trim and tilt / power
tilt models 
1. Place the gear shift lever in neutral.
ZMU02569
DN
ZMU01936
UPDN
DOWN
ZMU03410
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Operation 
41 
2. Slightly tilt the outboard motor up to the
desired position using the power trim / tilt
switch.3. To return the outboard motor to the nor-
mal running position, press the power
trim / tilt switch and slowly tilt the out-
board motor down. 
EMU28191 
Cruising in other conditions 
Cruising in salt water 
After operating in salt water, wash out the
cooling water passages with fresh water to
prevent them from becoming clogged with
salt deposits.
NOTE:
 
For cooling system flushing instructions, see 
page 43. 
Cruising in turbid water 
Yamaha strongly recommends that you use
the optional chromium-plated water pump kit
(not available for some models) if you use
the outboard motor in turbid (muddy) water
conditions.
UP
ZMU01935
UPDN
UP
ZMU03412
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42 
Maintenance 
EMU28217 
Specifications 
Dimension: 
Overall length:
40TR 646 mm (25.4 in)
50TR 670 mm (26.4 in)
Overall width:
40TR 350 mm (13.8 in)
50TR 360 mm (14.2 in)
Overall height L:
1319 mm (51.9 in)
Transom height L:
533 mm (21.0 in)
Weight (without propeller) L:
86.0 kg (190 lb) 
Performance: 
Full throttle operating range:
4500–5500 r/min
Maximum output:
40TR 29.4 kW@5000 r/min (40 
HP@5000 r/min)
50TR 36.8 kW@5000 r/min (50 
HP@5000 r/min)
Idling speed (in neutral):
800  
± 
50 r/min 
Engine: 
Type:
2-stroke L
Displacement:
698.0 cm 
3
 
 (42.59 cu.in)
Bore  
× 
 stroke:
67.0  
× 
 66.0 mm (2.64  
× 
 2.60 in)
Ignition system:
CDI
Spark plug (NGK):
40TR B7HS-10
50TR B8HS-10
Spark plug gap:
0.9–1.0 mm (0.035–0.039 in)
Control system:
Remote controlStarting system:
Electric
Starting carburetion system:
Prime start
Min. cold cranking amps (CCA/SAE):
245.0 A
Min. marine cranking amps (MCA/ABYC):
323.0 A
Min. reserve capacity (RC/SAE):
52 minutes
Alternator output for battery DC:
6.0 A 
Drive unit: 
Gear positions:
Forward-neutral-reverse
Gear ratio:
1.85 (24/13)
Trim and tilt system:
Power trim and tilt
Propeller mark:
G 
Fuel and oil: 
Recommended fuel:
Regular unleaded gasoline
Min. pump octane:
86
Fuel tank capacity:
25 L (6.60 US gal) (5.50 Imp.gal)
Recommended engine oil:
YAMALUBE 2-stroke outboard motor 
oil
Lubrication:
Oil injection
Engine oil tank capacity:
1.5 L (1.59 US qt) (1.32 Imp.qt)
Recommended gear oil:
Hypoid gear oil SAE#90
Gear oil quantity:
430.0 cm 
3
 
 (14.54 US oz) (15.17 
Imp.oz) 
Tightening torque for engine:✩✦✯✬✤✲✲✣ ✧✥ 	
 


 
						

							 
Maintenance 
43 
Spark plug:
25.0 Nm (18.4 ft-lb) (2.55 kgf-m)
Propeller nut:
35.0 Nm (25.8 ft-lb) (3.57 kgf-m) 
EMU28222 
Transporting and storing 
outboard motor
WARNING
 
EWM00690  
 
Leaking fuel is a fire hazard. When
transporting and storing the outboard
motor, close the air vent screw and fuel
cock to prevent fuel from leaking. 
 
USE CARE when transporting fuel tank,
whether in a boat or car. 
 
DO NOT fill fuel container to maximum
capacity. Gasoline will expand consid-
erably as it warms up and can build up
pressure in the fuel container. This can
cause fuel leakage and a potential fire 
hazard.
WARNING
 
EWM00700  
Never get under the lower unit while it is
tilted, even if a motor support bar is used.
Severe injury could occur if the outboard 
motor accidentally falls.
CAUTION:
 
ECM00660  
Do not use the tilt support lever or knob
when trailering the boat. The outboard
motor could shake loose from the tilt sup-
port and fall. If the motor cannot be trail-
ered in the normal running position, use
an additional support device to secure it 
in the tilt position. 
The outboard motor should be trailered and
stored in the normal running position. If there
is insufficient road clearance in this position,
then trailer the outboard motor in the tilt po-sition using a motor support device such as
a transom saver bar. Consult your Yamaha
dealer for further details. 
EMU28235 
Clamp screw mounting models 
When transporting or storing the outboard
motor while removed from a boat, keep the
outboard motor in the attitude shown.
NOTE:
 
Place a towel or something similar under the 
outboard motor to protect it from damage. 
EMU30272 
Storing outboard motor 
When storing your Yamaha outboard motor
for prolonged periods of time (2 months or
longer), several important procedures must
be performed to prevent excessive damage.
It is advisable to have your outboard motor
serviced by an authorized Yamaha dealer
prior to storage. However, you, the owner,
with a minimum of tools, can perform the fol-
lowing procedures.
CAUTION:
 
ECM01411  
 
Do not place the outboard motor on its
side before the cooling water has
drained from it completely, otherwise
water may enter the cylinder through
the exhaust port and cause engine trou-
ble. 
 
Store the outboard motor in a dry, well-
ZMU03122
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Maintenance 
44 
ventilated place, not in direct sunlight. 
EMU28301 
Procedure 
EMU28372 
Flushing in a test tank 
1. Wash the outboard motor body using
fresh water. For further information, see
page 46.
2. Fill the fuel tank with fresh fuel and add
one ounce of “Yamaha Fuel Conditioner
and Stabilizer” (Part No. LUB-FUELC-
12-00) to each gallon of fuel.
NOTE:
 
The use of “Yamaha Fuel Conditioner and
Stabilizer” eliminates the need to drain the
fuel system. Consult your Yamaha dealer or
other qualified mechanic if the fuel system is 
to be drained instead.
3. Remove the engine top cowling and si-
lencer cover.
4. Install the outboard motor on the test
tank.
5. Fill the tank with fresh water to above the
level of the anti-cavitation plate.
CAUTION:
 
ECM00300  
Do not run the engine without supplying
it with cooling water. Either the enginewater pump will be damaged or the en-
gine will be damaged from overheating.
Before starting the engine, be sure to
supply water to the cooling water passag- 
es.
CAUTION:
 
ECM00290  
If the fresh water level is below the level
of the anti-cavitation plate, or if the water
supply is insufficient, engine seizure may 
occur. 
6. Cooling system flushing is essential to
prevent the cooling system from clog-
ging up with salt, sand, or dirt. In addi-
tion, fogging of the engine is mandatory
to prevent excessive engine damage
due to rust. Perform the flushing and
fogging at the same time.
WARNING
 
EWM00090  
 
Do not touch or remove electrical parts
when starting or during operation. 
 
Keep hands, hair, and clothes away
from the flywheel and other rotating 
parts while the engine is running. 
7. Run the engine at a fast idle for 10–15
minutes in neutral position.
8. Just prior to turning off the engine, quick-
ly spray “Yamaha Stor-Rite Engine
Fogging Oil” (Part No. LUB-STRRT-12-
00) alternately into each carburetor or
the fogging hole of the silencer cover, if
equipped. When properly done, the en-
gine will smoke excessively and almost
stall.
9. Remove the outboard motor from the
test tank.
10. Drain the cooling water completely out
of the motor. Clean the body thoroughly.
11. Install the silencer cover/cap and top 
1. Water surface
2. Lowest water level
ZMU02051
1
2
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Maintenance 
45 
cowling. 
EMU28410 
Lubrication (oil injection models) 
1. Grease the spark plug threads and in-
stall the spark plug(s) and torque to
proper specification. For information on
spark plug installation, see page 49.
2. Fill the oil tanks. This prevents the for-
mation of condensation. For models with
a remote oil tank, it may be necessary to
manually override the control unit to
completely fill the engine oil tank.
3. Change the gear oil. For instructions,
see page 55. Inspect the oil for the pres-
ence of water which indicates a leaky
seal. Seal replacement should be per-
formed by an authorized Yamaha dealer
prior to use.
4. Grease all grease fittings. For further de-
tails, see page 49. 
EMU28421 
Cleaning and anticorrosion 
measures 
1. Wash down the exterior of the outboard
motor with fresh water and dry off com-
pletely.
2. Spray the outboard motor exterior with
“Yamaha Silicone Protectant” (Part No.
LUB-SILCNE-13-00).
3. Wax the cowling with a non-abrasive
wax such as “Yamaha Silicone Wax”
(Part No. ACC-11000-15-02). 
EMU28430 
Battery care
WARNING
 
EWM00330  
Battery electrolytic fluid is dangerous; it
contains sulfuric acid and therefore is
poisonous and highly caustic.
Always follow these preventive mea-
sures: 
 
Avoid bodily contact with electrolyticfluid as it can cause severe burns or
permanent eye injury. 
 
Wear protective eye gear when han-
dling or working near batteries.
Antidote (EXTERNAL): 
 
SKIN - Flush with water. 
 
EYES - Flush with water for 15 minutes
and get immediate medical attention.
Antidote (INTERNAL): 
 
Drink large quantities of water or milk
followed by milk of magnesia, beaten
egg, or vegetable oil. Get immediate
medical attention.
Batteries also generate explosive hydro-
gen gas; therefore, you should always
follow these preventive measures: 
 
Charge batteries in a well-ventilated ar-
ea. 
 
Keep batteries away from fire, sparks,
or open flames (for example: welding
equipment, lighted cigarettes, and so
on.) 
 
DO NOT SMOKE when charging or han-
dling batteries.
KEEP BATTERIES AND ELECTROLYTIC 
FLUID OUT OF REACH OF CHILDREN. 
Batteries vary among manufacturers. There-
fore the following procedures may not al-
ways apply. Consult your battery
manufacturer’s instructions.
Procedure
1. Disconnect and remove the battery from
the boat. Always disconnect the black
negative cable first to prevent the risk of
shorting.
2. Clean the battery casing and terminals.
Fill each cell to the upper level with dis-
tilled water.
3. Store the battery on a level surface in a
cool, dry, well-ventilated place out of di-
rect sunlight.
✩✦✯✬✤✲✲✣ ✧