2008 YAMAHA PW50 Owners Manual

PERIODIC MAINTENANCE AND MINOR REPAIR
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EAU19603
Checking the spark plug
The spark plug is an important engine
component, which is easy to check.
Since heat and deposits will cause any
spark plug to slowly erode, the spark
plug should be removed and checked
in accordance with the periodic mainte-
nance and lubrication chart. In addition,
the condition of the spark plug can re-
veal the condition of the engine.
To remove the spark plug
1. Remove the spark plug cap.
2. Remove the spark plug as shown,
with the spark plug wrench includ-
ed in the owner’s tool kit.
To check the spark plug
1. Check that the porcelain insulator
around the center electrode of the
spark plug is a medium-to-light tan
(the ideal color when the vehicle is
ridden normally).
NOTE:

If the spark plug shows a distinctly dif-
ferent color, the engine could be oper-
ating improperly. Do not attempt to
diagnose such problems yourself. In-
stead, have a Yamaha dealer check
the vehicle.
2. Check the spark plug for electrode
erosion and excessive carbon or
other deposits, and replace it ifnecessary.
To install the spark plug
1. Measure the spark plug gap with a
wire thickness gauge and, if nec-
essary, adjust the gap to specifica-
tion.
2. Clean the surface of the spark plug
1. Spark plug cap
1

1. Spark plug wrench
1

Specified spark plug:
NGK/BP4HS (AUS)(NZL)
NGK/BPR4HS
(AUT)(BEL)(CAN)(CHE)(DEU)
(DNK)(ESP)(FIN)(FRA)(GBR)(GRC)
(IRL)(NLD)(NOR)(PRT)(SWE)(ZAF)
DENSO/W14FPL (AUS)(NZL)
1. Spark plug gap
Spark plug gap:
0.6–0.7 mm (0.024–0.028 in)
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gasket and its mating surface, and
then wipe off any grime from the
spark plug threads.
3. Install the spark plug with the
spark plug wrench, and then tight-
en it to the specified torque.
NOTE:

If a torque wrench is not available when
installing a spark plug, a good estimate
of the correct torque is 1/4–1/2 turn
past finger tight. However, the spark
plug should be tightened to the speci-
fied torque as soon as possible.
4. Install the spark plug cap.
EAU41100
Removing the power
reduction plate
To obtain full engine performance ca-
pability, removing the power reduction
plate is required.
WARNING

EWA14580
Always let the exhaust system cool
prior to touching exhaust compo-
nents.
1. Remove the exhaust manifold by
removing the bolts.
2. Remove the gasket.
3. Remove the power reduction
plate.
NOTE:

Store the power reduction plate with the
owner’s manual so that it is readily
available whenever you want to reduce
the engine power.
4. Install the exhaust manifold by in-
stalling the bolts.
Tightening torque:
Spark plug:
20 Nm (2.0 m·kgf, 14.5 ft·lbf)
1. Exhaust manifold bolt
1

1. Exhaust manifold
2. Gasket
3. Power reduction plate
Tightening torque:
Exhaust manifold bolt:
8.5 Nm (0.9 m·kgf, 6.1 ft·lbf)
1
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EAU40891
Transmission oil
The transmission oil must be checked
for oil leakage before each ride. If any
leakage is found, have a Yamaha deal-
er check and repair the motorcycle. In
addition, the transmission oil must be
changed at the intervals specified in the
periodic maintenance and lubrication
chart.
1. Place the motorcycle on the cen-
terstand.
2. Place an oil pan under the trans-
mission to collect the used oil.
3. Remove the oil filler cap and drain
bolt to drain the oil from the trans-
mission.4. Install the transmission oil drain
bolt, and then tighten it to the spec-
ified torque.
5. Add the specified amount of the
recommended transmission oil,
and then install and tighten the oil
filler cap.
CAUTION:

ECA10452

In order to prevent clutch slip-
page (since the transmission oil
also lubricates the clutch), do
not mix any chemical additives.
Do not use oils with a diesel
specification of “CD” or oils of a
higher quality than specified. In
addition, do not use oils labeled
“ENERGY CONSERVING II” or
higher.

Make sure that no foreign mate-
rial enters the transmission.
6. Start the engine, and then let it idle
for several minutes while checking
the transmission for oil leakage. If
oil is leaking, immediately turn the
engine off and check for the cause.
1. Transmission oil filler cap
1

1. Transmission oil drain bolt
Tightening torque:
Transmission oil drain bolt:
14 Nm (1.4 m·kgf, 10.1 ft·lbf)
Recommended transmission oil:
See page 8-1.
Oil change quantity:
0.30 L (0.32 US qt) (0.26 Imp.qt)
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EAU41711
Middle and final gear cases
The middle and final gear cases must
be checked for grease leakage before
each ride. If any leakage is found, have
a Yamaha dealer check and repair the
motorcycle. In addition, have a
Yamaha dealer check and lubricate the
middle and final gears at the intervals
specified in the periodic maintenance
and lubrication chart.
EAU40901
Cleaning the air filter element
The air filter element should be cleaned
at the intervals specified in the periodic
maintenance and lubrication chart.
Clean the air filter element more fre-
quently if you are riding in unusually
wet or dusty areas.
1. Remove the seat. (See page 3-7.)
2. Remove the air filter case cover by
removing the screw.
3. Pull the sponge material out, clean
it with solvent, and then squeeze
the remaining solvent out.4. Apply oil of the recommended type
to the entire surface of the sponge
material, and then squeeze the ex-
cess oil out.
NOTE:

The sponge material should be wet but
1. Air filter case cover
2. Screw
2 1

1. Sponge material
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not dripping.
5. Insert the sponge material into the
air filter case.
CAUTION:

ECA15620

Make sure that the sponge ma-
terial is properly seated in the
air filter case.

The engine should never be op-
erated without the sponge mate-
rial installed, otherwise the
piston(s) and/or cylinder(s) may
become excessively worn.
6. Install the air filter case cover by in-
stalling the screw.
7. Install the seat.
EAU41220
Cleaning the spark arrester
The spark arrester should be cleaned
at the intervals specified in the periodic
maintenance and lubrication chart.
WARNING

EWA10980

Always let the exhaust system
cool prior to touching exhaust
components.

Do not start the engine when
cleaning the exhaust system.
NOTE:

Make sure to select a well-ventilated
area free of combustible materials to
clean the spark arrester.
1. Remove the tailpipe by removing
the screw, and then pulling it out of
the muffler.2. Tap the tailpipe lightly, and then
use a wire brush to remove any
carbon deposits from the spark ar-
rester portion of the tailpipe and in-
side of the tailpipe housing.
Recommended oil:
Yamaha foam air filter oil or other
quality foam air filter oil
1. Tailpipe
2. Screw
3. Muffler
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3. Insert the tailpipe into the muffler,
and then install and tighten the
screw.
NOTE:

Make sure to align the screw hole when
inserting the tailpipe.
EAU39930
Adjusting the carburetor
The carburetor is an important part of
the engine and requires very sophisti-
cated adjustment. Therefore, most car-
buretor adjustments should be left to a
Yamaha dealer, who has the neces-
sary professional knowledge and expe-
rience. The adjustment described in the
following section, however, may be ser-
viced by the owner as part of routine
maintenance.
CAUTION:

ECA10550
The carburetor has been set and ex-
tensively tested at the Yamaha fac-
tory. Changing these settings
without sufficient technical knowl-
edge may result in poor perfor-
mance of or damage to the engine.
EAU21360
Adjusting the engine idling
speed
The engine idling speed must be
checked and, if necessary, adjusted as
follows at the intervals specified in the
periodic maintenance and lubrication
chart.
NOTE:

A diagnostic tachometer is needed to
make this adjustment.
1. Attach the tachometer to the spark
plug lead.
2. Start the engine and warm it up
for several minutes at 1000–2000
r/min while occasionally revving it
to 4000–5000 r/min.
NOTE:

The engine is warm when it quickly re-
sponds to the throttle.
3. Check the engine idling speed
and, if necessary, adjust it to spec-
ification by turning the throttle stop
screw. To increase the engine
idling speed, turn the screw in di-
rection (a). To decrease the en-
gine idling speed, turn the screw in
1. Spark arrester
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direction (b).
NOTE:

If the specified idling speed cannot be
obtained as described above, have a
Yamaha dealer make the adjustment.
EAU21382
Checking the throttle cable
free play
The throttle cable free play should mea-
sure 1.5–3.5 mm (0.06–0.14 in) at the
throttle grip. Periodically check the
throttle cable free play and, if neces-
sary, have a Yamaha dealer adjust it.
EAU40910
Tires
To maximize the performance, durabil-
ity, and safe operation of your motorcy-
cle, note the following points regarding
the specified tires.
Tire air pressure
The tire air pressure should be checked
and, if necessary, adjusted before each
ride.
WARNING

EWA14380

The tire air pressure must be
checked and adjusted on cold
tires (i.e., when the temperature
of the tires equals the ambient
temperature).

The tire air pressure must be ad-
justed in accordance with the
weight of the rider, the riding
speed, and the riding condi-
tions.
1. Throttle stop screw
Engine idling speed:
1650–1750 r/min
1(a) (b)

1. Throttle cable free play1
Standard tire air pressure:
Front:
100 kPa (15 psi) (1.00 kgf/cm
2

)
Rear:
100 kPa (15 psi) (1.00 kgf/cm
2

)

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9Tire inspection
The tires must be checked before each
ride. If the center tread depth reaches
the specified limit, if the tire has a nail or
glass fragments in it, or if the sidewall is
cracked, have a Yamaha dealer re-
place the tire immediately.
Tire information
This motorcycle is equipped with panel
wheels and tube tires.
WARNING

EWA10460

The front and rear tires should
be of the same make and de-
sign, otherwise the handling
characteristics of the vehicle
cannot be guaranteed.

After extensive tests, only the
tires listed below have been ap-
proved for this model by
Yamaha Motor Co., Ltd.
WARNING

EWA14390

Have a Yamaha dealer replace
excessively worn tires. Operat-
ing the motorcycle with exces-sively worn tires decreases
riding stability and can lead to
loss of control.

The replacement of all
wheel-and brake-related parts,
including the tires, should be
left to a Yamaha dealer, who has
the necessary professional
knowledge and experience.

It is not recommended to patch
a punctured tube. If unavoid-
able, however, patch the tube
very carefully and replace it as
soon as possible with a
high-quality product.
1. Tire sidewall
2. Tire tread depth
Minimum tire tread depth (front and
rear):
4.0 mm (0.16 in)
12

Front tire:
Size:
2.50-10 4PR
Manufacturer/model:
BRIDGESTONE/KNOBBY
IRC/KNOBBY
Rear tire:
Size:
2.50-10 4PR
Manufacturer/model:
BRIDGESTONE/KNOBBY
IRC/KNOBBY