Yamaha Wr 450 F Owners Manual

							3 - 46
INSP
ADJ
STEERING HEAD INSPECTION AND ADJUSTMENT
Tighten the ring nut 3 using ring nut
wrench 4.
NOTE:
Set the torque wrench to the ring nut wrench
so that they form a right angle.
Ring nut wrench:
YU-33975/90890-01403
T R..
Ring nut (initial tightening):
38 Nm (3.8 m • kg, 27 ft • lb)
Loosen the ring nut one turn.
Retighten the ring nut using the ring nut
wrench.
WARNING
Avoid over-tightening.
T R..
Ring nut (final tightening):
7 Nm (0.7 m • kg, 5.1 ft • lb)
Check the steering shaft by turning it lock
to lock. If there is any binding, remove the
steering shaft assembly and inspect the
steering bearings.
Install the plain washer 5, handle crown
6, plain washer 7, steering shaft nut 8,
steering shaft cap 9, handlebar 0, han-
dlebar holder A and headlight B.
NOTE:
The handlebar holder should be installed
with the punched mark a forward.
Insert the end of the fuel breather hose C
into the hole in the steering shaft cap.
CAUTION:
First tighten the bolts on the front side of
the handlebar holder, and then tighten
the bolts on the rear side.
T R..
Steering shaft nut:
145 Nm (14.5 m • kg, 105 ft • lb)
Handlebar holder:
28 Nm (2.8 m • kg, 20 ft • lb)
Pinch bolt (handle crown):
23 Nm (2.3 m • kg, 17 ft • lb)
Headlight (left and right):
10 Nm (1.0 m • kg, 7.2 ft • lb)
Headlight (lower):
7 Nm (0.7 m • kg, 5.1 ft • lb) 
						

							3 - 47
INSP
ADJ
LUBRICATION
LUBRICATION
To ensure smooth operation of all compo-
nents, lubricate your machine during setup,
after break-in, and after every race.
1All control cable
2Clutch lever pivot
3Shift pedal pivot
4Footrest pivot
5Throttle-to-handlebar contact
6Drive chain
7Tube guide cable winding portion
8Throttle cable end
9Clutch cable end
0Hot starter cable endÅUse Yamaha cable lube or equivalent on these
areas.
ıUse SAE 10W-30 motor oil or suitable chain
lubricants.
ÇLubricate the following areas with high quality,
lightweight lithium-soap base grease.
CAUTION:
Wipe off any excess grease, and avoid get-
ting grease on the brake discs.
AAA
AAB
CC 
						

							3 - 48
INSP
ADJ
ELECTRICAL/SPARK PLUG INSPECTION
EC370000
ELECTRICAL
EC371001
SPARK PLUG INSPECTION
1. Remove:
Spark plug
2. Inspect:
Electrode 1 
Wear/damage → Replace.
Insulator color 2 
Normal condition is a medium to light
tan color.
Distinctly different color → Check the
engine condition.
NOTE:
When the engine runs for many hours at low
speeds, the spark plug insulator will become
sooty, even if the engine and carburetor are in
good operating condition.
3. Measure:
Plug gap a 
Use a wire gauge or thickness gauge.
Out of specification → Regap.
Spark plug gap:
0.7 ~ 0.8 mm (0.028 ~ 0.031 in)
4. Clean the plug with a spark plug cleaner
if necessary.
5. Tighten:
Spark plug
NOTE:
Before installing a spark plug, clean the gas-
ket surface and plug surface.
Finger-tighten a the spark plug before
torquing to specification b.
T R..13 Nm (1.3 m · kg, 9.4 ft · lb) 
						

							3 - 49
INSP
ADJ
IGNITION TIMING CHECK
IGNITION TIMING CHECK
1. Remove:
Timing plug 1 
1
2. Attach:
Timing light 
Inductive tachometer 
To the ignition coil lead (orange lead
1).
3. Check:
Ignition timing
Timing light:
YM-33277-A/90890-03141
Inductive tachometer:
YU-8036-B
Engine tachometer:
90890-03113
Checking steps:
Start the engine and let it warm up. Let the
engine run at the specified speed.
Adjust the engine idling speed.
Refer to “IDLE SPEED ADJUSTMENT”
section.
Visually check the stationary pointer a is
within the firing range b on the rotor.
Incorrect firing range → Check rotor and
pickup assembly.
1
4. Install:
Timing plug 
						

							3 - 50
INSP
ADJ
BATTERY INSPECTION AND CHARGING
WARNING
Batteries generate explosive hydrogen gas
and contain electrolyte which is made of
poisonous and highly caustic sulfuric acid. 
Therefore, always follow these preventive
measures: 
Wear protective eye gear when handling
or working near batteries. 
Charge batteries in a well-ventilated area. 
Keep batteries away from fire, sparks or
open flames (e.g., welding equipment,
lighted cigarettes). 
DO NOT SMOKE when charging or han-
dling batteries. 
KEEP BATTERIES AND ELECTROLYTE
OUT OF REACH OF CHILDREN. 
Avoid bodily contact with electrolyte as it
can cause severe burns or permanent eye
injury. 
FIRST AID IN CASE OF BODILY CONTACT: 
EXTERNAL 
Skin — Wash with water. 
Eyes — Flush with water for 15 minutes
and get immediate medical attention. 
INTERNAL 
Drink large quantities of water or milk fol-
lowed with milk of magnesia, beaten egg
or vegetable oil. Get immediate medical
attention. 
CAUTION:
Charging time, charging amperage and
charging voltage for an MF battery are dif-
ferent from those of conventional batteries.
The MF battery should be charged as
explained in the charging method illustra-
tions. If the battery is overcharged, the
electrolyte level will drop considerably.
Therefore, take special care when charging
the battery. 
BATTERY INSPECTION AND CHARGING 
						

							3 - 51
INSP
ADJ
BATTERY INSPECTION AND CHARGING
NOTE:
Since MF batteries are sealed, it is not possi-
ble to check the charge state of the battery by
measuring the specific gravity of the electro-
lyte. Therefore, the charge of the battery has
to be checked by measuring the voltage at the
battery terminals. 
1. Remove: 
Seat
2. Disconnect: 
Battery leads
(from the battery terminals)
CAUTION:
First, disconnect the negative battery lead
1, and then the positive battery lead 2.
3. Remove: 
Battery band
Battery
4. Measure: 
Battery charge
Measurement steps:
Connect a pocket tester 1 to the battery
terminals. 
Tester positive probe → 
battery positive terminal
Tester negative probe → 
battery negative terminal
NOTE:
The charge state of an MF battery can be
checked by measuring its open-circuit
voltage (i.e., the voltage when the positive
terminal is disconnected). 
No charging is necessary when the open-
circuit voltage equals or exceeds 12.8 V.  
						

							3 - 52
INSP
ADJ
BATTERY INSPECTION AND CHARGING
ÅRelationship between the open-circuit voltage
and the charging time at 20 ˚C (68 ˚F)
(These values vary with the temperature, the
condition of the battery plates, and the electro-
lyte level.)
ıOpen-circuit voltage
ÇCharging time (hours)
ÎTime (minutes)
‰Charging condition of the battery
ÏAmbient temperature 20 ˚C (68 ˚F)
aCharging
bCheck the open-circuit voltage.
5. Charge: 
Battery 
(refer to the appropriate charging
method illustration)
WARNING
Do not quick charge a battery. 
CAUTION:
Never remove the MF battery sealing
caps. 
Do not use a high-rate battery charger
since it forces a high-amperage current
into the battery quickly and can cause
battery overheating and battery plate
damage. 
If it is impossible to regulate the charging
current on the battery charger, be careful
not to overcharge the battery. 
When charging a battery, be sure to
remove it from the machine. (If charging
has to be done with the battery mounted
on the machine, disconnect the negative
battery lead from the battery terminal.) 
To reduce the chance of sparks, do not
plug in the battery charger until the bat-
tery charger leads are connected to the
battery. 
Check the charge of the battery, as shown
in the charts and the following example.
Example
Open-circuit voltage = 12.0 V 
Charging time = 6.5 hours 
Charge of the battery = 20 ~ 30% Å 
						

							3 - 53
INSP
ADJ
BATTERY INSPECTION AND CHARGING
Before removing the battery charger lead
clips from the battery terminals, be sure
to turn off the battery charger. 
Make sure the battery charger lead clips
are in full contact with the battery termi-
nal and that they are not shorted. A cor-
roded battery charger lead clip may
generate heat in the contact area and a
weak clip spring may cause sparks. 
If the battery becomes hot to the touch at
any time during the charging process,
disconnect the battery charger and let the
battery cool before reconnecting it. Hot
batteries can explode! 
As shown in the following illustration, the
open-circuit voltage of an MF battery sta-
bilizes about 30 minutes after charging
has been completed. Therefore, wait
30 minutes after charging is completed
before measuring the open-circuit volt-
age.  
						

							3 - 54
INSP
ADJ
BATTERY INSPECTION AND CHARGING
Charging method using a variable voltage charger 
						

							3 - 55
INSP
ADJ
BATTERY INSPECTION AND CHARGING
Charging method using a constant voltage charger