engine YAMAHA PW50 2008 Owners Manual
Page 10 of 70
 
TABLE OF CONTENTS 
SAFETY INFORMATION 
 ...................1-1
Safe riding ........................................1-1
Location of important labels .............1-4 
DESCRIPTION 
 ...................................2-1
Left view ...........................................2-1
Right view .........................................2-2
Controls and instruments..................2-3 
INSTRUMENT AND CONTROL 
FUNCTIONS 
........................................3-1
Handlebar switch  .............................3-1
Speed limiter and power reduction 
plate .............................................3-1
Front brake lever  .............................3-2
Rear brake lever  ..............................3-3
Fuel tank cap  ...................................3-3
Fuel ..................................................3-3
Fuel tank breather hose ...................3-5
2-stroke engine oil  ...........................3-5
Fuel cock  .........................................3-5
Starter (choke) lever “ 
1 
” .................3-6
Kickstarter ........................................3-6
Seat .................................................3-7 
PRE-OPERATION CHECKS 
...............4-1
Pre-operation check list  ...................4-2 
OPERATION AND IMPORTANT 
RIDING POINTS 
.................................. 5-1
Starting and warming up a cold 
engine .......................................... 5-1
Starting a warm engine  ................... 5-1
Starting off  ....................................... 5-2
Acceleration and deceleration  ......... 5-2
Braking ............................................ 5-2
Engine break-in  ............................... 5-3
Parking ............................................ 5-4 
PERIODIC MAINTENANCE AND 
MINOR REPAIR 
.................................. 6-1
Owner’s tool kit ................................ 6-1
Periodic maintenance chart for the 
emission control system  .............. 6-2
General maintenance and lubrication 
chart ............................................. 6-3
Checking the spark plug .................. 6-5
Removing the power reduction 
plate ............................................. 6-6
Transmission oil  .............................. 6-7
Middle and final gear cases  ............ 6-8
Cleaning the air filter element  ......... 6-8
Cleaning the spark arrester  ............. 6-9
Adjusting the carburetor  ................ 6-10
Adjusting the engine idling 
speed ......................................... 6-10
Checking the throttle cable free 
play ............................................ 6-11
Tires .............................................. 6-11Panel wheels ................................. 6-13
Accessories and replacement 
parts ........................................... 6-13
Adjusting the front and rear brake 
lever free play  ............................ 6-14
Checking the front and rear brake 
shoes ......................................... 6-15
Checking and lubricating the 
cables ........................................ 6-15
Checking and lubricating the throttle 
grip and cable  ............................ 6-16
Adjusting the Autolube pump  ........ 6-16
Lubricating the front and rear brake 
levers ......................................... 6-16
Checking and lubricating the 
centerstand ................................ 6-17
Checking the front fork  .................. 6-17
Checking the steering  ................... 6-18
Checking the wheel bearings  ........ 6-18
Front wheel  ................................... 6-19
Rear wheel  .................................... 6-20
Troubleshooting ............................ 6-23
Troubleshooting chart  ................... 6-24  
MOTORCYCLE CARE AND 
STORAGE  
........................................... 7-1
Matte color caution .......................... 7-1
Care ................................................ 7-1
Storage ........................................... 7-3  
SPECIFICATIONS  
 ............................. 8-1 
Page 12 of 70
 
1-1 
1 
SAFETY INFORMATION  
EAU40931 
Safe riding 
 
Always make pre-operation
checks. Careful checks may help
prevent an accident. 
 
This motorcycle is designed for
off-road use only, therefore, it is il-
legal to operate it on public streets,
roads, or highways, even a dirt or
gravel one. Off-road use on public
lands may be illegal. Please check
local regulations before riding. 
 
This motorcycle is designed to car-
ry the operator only. No passen-
gers. 
 
Many accidents involve inexperi-
enced operators. 
 
Make sure that the operator is
qualified and that you only lend
your motorcycle to other quali-
fied operators. 
 
Know your skills and limits.
Staying within your limits may
help you to avoid an accident. 
 
Many accidents have been caused
by error of the motorcycle opera-
tor. A typical error made by the op-
erator is veering wide on a turn
due to EXCESSIVE SPEED or un-dercornering (insufficient lean an-
gle for the speed). Never travel
faster than warranted by condi-
tions. 
 
Ride cautiously in unfamiliar ar-
eas. You may encounter hidden
obstacles that could cause an ac-
cident. 
 
The posture of the operator is im-
portant for proper control. The op-
erator should keep both hands on
the handlebar and both feet on the
operator footrests during operation
to maintain control of the motorcy-
cle. 
 
Never ride under the influence of
alcohol or other drugs. 
Protective apparel 
The majority of fatalities from motorcy-
cle accidents are the result of head in-
juries. The use of a safety helmet is the
single most critical factor in the preven-
tion or reduction of head injuries. 
 
Always wear an approved helmet. 
 
Wear a face shield or goggles.
Wind in your unprotected eyes
could contribute to an impairmentof vision that could delay seeing a
hazard. 
 
The use of a jacket, heavy boots,
trousers, gloves, etc., is effective in
preventing or reducing abrasions
or lacerations. 
 
Never wear loose-fitting clothes,
otherwise they could catch on the
control levers, footrests, or wheels
and cause injury or an accident. 
 
Never touch the engine or exhaust
system during or after operation.
They become very hot and can
cause burns. Always wear protec-
tive clothing that covers your legs,
ankles, and feet.  
Modifications  
Modifications made to this motorcycle
not approved by Yamaha, or the re-
moval of original equipment, may ren-
der the motorcycle unsafe for use and
may cause severe personal injury.
Modifications may also make your mo-
torcycle illegal to use.  
Loading and accessories  
Adding accessories to your motorcycle 
Page 14 of 70
 
SAFETY INFORMATION 
1-3 
1 
engine power. 
Gasoline and exhaust gas 
 
GASOLINE IS HIGHLY FLAMMA-
BLE: 
 
Always turn the engine off when
refueling. 
 
Take care not to spill any gaso-
line on the engine or exhaust
pipe/muffler when refueling. 
 
Never refuel while smoking or in
the vicinity of an open flame. 
 
Never start the engine or let it run
for any length of time in a closed
area. The exhaust fumes are poi-
sonous and may cause loss of
consciousness and death within a
short time. Always operate your
motorcycle in an area that has ad-
equate ventilation. 
 
Always turn the engine off before
leaving the motorcycle unattend-
ed. When parking the motorcycle,
note the following: 
 
The engine and exhaust pipe/
muffler may be hot, therefore,
park the motorcycle in a place
where pedestrians or childrenare not likely to touch these hot
areas. 
 
Do not park the motorcycle on a
slope or soft ground, otherwise it
may fall over. 
 
Do not park the motorcycle near
a flammable source (e.g., a ker-
osene heater, or near an open
flame), otherwise it could catch
fire. 
 
When transporting the motorcycle
in another vehicle, make sure that
it is kept upright and that the fuel
cock is turned to “S” (stop). If the
motorcycle should lean over, gas-
oline may leak out of the carbure-
tor or fuel tank. 
 
If you should swallow any gaso-
line, inhale a lot of gasoline vapor,
or allow gasoline to get into your
eyes, see your doctor immediate-
ly. If any gasoline spills on your
skin or clothing, immediately wash
the affected area with soap and
water and change your clothes. 
Page 21 of 70
 
DESCRIPTION 
2-2 
2
3
4
5
6
7
8
9
 
EAU10420 
Right view
3
12
4
 
1. Spark arrester (page 6-9)
2. Seat (page 3-7)
3. Transmission oil filler cap (page 6-7)
4. 2-stroke engine oil tank (page 3-5) 
Page 22 of 70
 
DESCRIPTION 
2-3 
1
2
3
4
5
6
7
8
9
 
EAU10430 
Controls and instruments
12
7 345
6
 
1. Rear brake lever (page 3-3)
2. Starter (choke) lever (page 3-6)
3. 2-stroke engine oil tank cap (page 3-5)
4. Right handlebar switch (page 3-1)
5. Front brake lever (page 3-2)
6. Throttle grip (page 6-11)
7. Fuel tank cap (page 3-3) 
Page 23 of 70
 
3-1 
2
34
5
6
7
8
9
 
INSTRUMENT AND CONTROL FUNCTIONS 
EAU40660 
Handlebar switch  
EAU40673 
Engine stop switch “OFF/RUN/
START”  
Set this switch to “START” before start-
ing the engine. Set this switch to “RUN”
after warming up the engine or before
starting off. Set this switch to “OFF” to
stop the engine.
NOTE:
 
 
The engine cannot be started with
this switch set to the “RUN” posi-
tion. 
 
The engine speed is limited while
this switch is set to the “START”
position, therefore the motorcyclecannot be ridden in that switch po- 
sition. 
EAU41041 
Speed limiter and power 
reduction plate  
Your motorcycle was delivered with an
adjustable speed limiter and a power
reduction plate. The speed limiter
keeps the throttle from fully opening,
even when the throttle grip is turned to
the maximum. The power reduction
plate is installed in the exhaust mani-
fold to limit the amount of power avail-
able while they learn.  
Speed limiter  
1. Loosen the locknut.
2. To increase the maximum engine
power available and the maximum
speed of the motorcycle, turn the
adjusting screw in direction (a). To
decrease the maximum engine
power available and the maximum
speed of the motorcycle, turn the
adjusting screw in direction (b). 
1. Engine stop switch “OFF/RUN/START”
1 
Page 26 of 70
 
INSTRUMENT AND CONTROL FUNCTIONS 
3-4 
1
2
3
4
5
6
7
8
9
CAUTION:
 
 ECA10070 
Immediately wipe off spilled fuel
with a clean, dry, soft cloth, since
fuel may deteriorate painted surfac- 
es or plastic parts. 
EAU41980 
For Canada
CAUTION:
 
 ECA15590 
Use only unleaded gasoline. The use
of leaded gasoline will cause severe
damage to internal engine parts,
such as the piston rings as well as to 
the exhaust system. 
Your Yamaha engine has been de-
signed to use regular unleaded gaso-
line with a pump octane number
[(R+M)/2] of 86 or higher, or a research
octane number of 91 or higher. Ifknocking (or pinging) occurs, use a
gasoline of a different brand or premi-
um unleaded fuel. Use of unleaded fuel
will extend spark plug life and reduce
maintenance cost. 
Gasohol 
There are two types of gasohol: gaso-
hol containing ethanol and that contain-
ing methanol. Gasohol containing
ethanol can be used if ethanol content
does not exceed 10%. Gasohol con-
taining methanol is not recommended
by Yamaha because it can cause dam-
age to the fuel system or vehicle perfor-
mance problems. 
Except for Canada
CAUTION:
 
 ECA15590 
Use only unleaded gasoline. The useof leaded gasoline will cause severe
damage to internal engine parts,
such as the piston rings as well as to 
the exhaust system.  
Your Yamaha engine has been de-
signed to use regular unleaded gaso-
line with a research octane number of
91 or higher. If knocking (or pinging) oc-
curs, use a gasoline of a different brand
or premium unleaded fuel. Use of un-
leaded fuel will extend spark plug life
and reduce maintenance costs. 
Recommended fuel: 
REGULAR UNLEADED GASOLINE 
ONLY 
Fuel tank capacity: 
2.0 L (0.53 US gal) (0.44 Imp.gal) 
Recommended fuel: 
For Europe: REGULAR UNLEADED 
GASOLINE ONLY
Except for Canada and Europe: UN-
LEADED GASOLINE ONLY 
Fuel tank capacity: 
2.0 L (0.53 US gal) (0.44 Imp.gal) 
Page 27 of 70
 
INSTRUMENT AND CONTROL FUNCTIONS 
3-5 
2
34
5
6
7
8
9
 
EAU13412 
Fuel tank breather hose  
Before operating the motorcycle: 
 
Check the fuel tank breather hose
connection. 
 
Check the fuel tank breather hose
for cracks or damage, and replace
it if damaged. 
 
Make sure that the fuel tank
breather hose is not blocked, and
clean it if necessary. 
EAU13452 
2-stroke engine oil  
Make sure that there is sufficient
2-stroke engine oil in the oil tank. Add
the recommended 2-stroke engine oil
as necessary.
NOTE:
 
Make sure that the 2-stroke engine oil 
tank cap is properly installed. 
EAU40701 
Fuel cock  
The fuel cock supplies fuel from the
tank to the carburetor while filtering it al-
so.
The fuel cock has two positions:  
S (stop)  
With the lever in this position, fuel will
not flow. Always return the lever to this
position when the engine is not running. 
1. Fuel tank breather hose
1
 
1. 2-stroke engine oil tank cap
2. Minimum level mark 
Recommended oil: 
See page 8-1. 
Oil quantity: 
0.30 L (0.32 US qt) (0.26 Imp.qt)
21
 
1. Arrow mark pointing to “S” (stop)
1 
Page 28 of 70
 
INSTRUMENT AND CONTROL FUNCTIONS 
3-6 
1
2
3
4
5
6
7
8
9O (on) 
With the lever in this position, fuel flows
to the carburetor. Normal riding is done
with the lever in this position.
 
EAU13590 
Starter (choke) lever “”  
Starting a cold engine requires a richer
air-fuel mixture, which is supplied by
the starter (choke).
Move the lever in direction (a) to turn on
the starter (choke).
Move the lever in direction (b) to turn off
the starter (choke). 
EAU13680 
Kickstarter  
To start the engine, fold out the kick-
starter lever, move it down lightly with
your foot until the gears engage, and
then push it down smoothly but force-
fully. 
1. Arrow mark pointing to “O” (on)
1
 
1. Starter (choke) lever “”
1 (a)
(b)
 
1. Kickstarter
1 
Page 31 of 70
 
PRE-OPERATION CHECKS 
4-2 
2
3
45
6
7
8
9
 
EAU15605 
Pre-operation check list  
ITEM CHECKS PAGE
Fuel 
 
Check fuel level in fuel tank. 
 
Refuel if necessary. 
 
Check fuel line for leakage.3-3  
2-stroke engine oil 
 
Check oil level in oil tank. 
 
If necessary, add recommended oil to specified level. 
 
Check vehicle for oil leakage.3-5  
Middle and final gear cases 
 
Check vehicle for grease leakage. 6-8 
Front brake 
 
Check operation. 
 
Lubricate cable if necessary. 
 
Check lever free play. 
 
Adjust if necessary.6-14, 6-15  
Rear brake 
 
Check operation. 
 
Lubricate cable if necessary. 
 
Check lever free play. 
 
Adjust if necessary.6-14, 6-15  
Throttle grip 
 
Make sure that operation is smooth. 
 
Check cable free play. 
 
If necessary, have Yamaha dealer adjust cable free play and lubricate cable 
and grip housing.6-11, 6-16  
Control cables 
 
Make sure that operation is smooth. 
 
Lubricate if necessary.6-15  
Wheels and tires 
 
Check for damage. 
 
Check tire condition and tread depth. 
 
Check air pressure. 
 
Correct if necessary.6-11, 6-13  
Brake levers 
 
Make sure that operation is smooth. 
 
Lubricate lever pivoting points if necessary.6-16  
Centerstand 
 
Make sure that operation is smooth. 
 
Lubricate pivot if necessary.6-17