Yamaha WR450FX, Owner'S Service Manual

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3-20
CHASSIS
3. Inspect:
• Brake fluid level
Refer to "CHECKING THE
BRAKE FLUID LEVEL" section.
4. Check:
•
Brake pedal operation
A softy or spongy feeling
→
Bleed
brake system.
Refer to "BLEEDING THE HY-
DRAULIC BRAKE SYSTEM" sec-
tion.
CHECKING THE REAR BRAKE
PAD INSULATOR
1. Remove:
• Brake pad
Refer to "CHECKING AND RE-
PLACING THE REAR BRAKE
PADS" section.
2. Inspect:
•
Rear brake pad insulator "1"
Damage
→
Replace.
CHECKING THE BRAKE FLUID
LEVEL
1. Place the brake master cylinder
so that its top is in a horizontal po-
sition.
2. Inspect:
•
Brake fluid level
Fluid at lower level
→
Fill up.
•
Use only designated quality
brake fluid to avoid poor brake
performance.
• Refill with same type and brand
of brake fluid; mixing fluids
could result in poor brake perfor-
mance.
• Be sure that water or other con-
taminants do not enter master
cylinder when refilling.
•
Clean up spilled fluid immediate-
ly to avoid erosion of painted
surfaces or plastic parts.
a. Lower level
A. Front
B. Rear
CHECKING THE SPROCKET
1. Inspect:
•
Sprocket teeth "a"
Excessive wear
→
Replace.
Replace the drive sprocket, rear
wheel sprocket and drive chain as a
set.
CHECKING THE DRIVE CHAIN
1. Measure:
•
Drive chain length (15 links) "a"
Out of specification
→
Replace.
• While measuring the drive chain
length, push down on the drive
chain to increase its tension.
•
Measure the length between drive
chain roller "1" and "16" as shown.
•
Perform this measurement at two or
three different places.
2. Remove:
•
Drive chain "1"
Remove the drive chain using a drive
chain cutter "2".
3. Clean:
•
Drive chain
Brush off as much dirt as possi-
ble. Then clean the drive chain
using the chain cleaner.
This machine has a drive chain
with small rubber O-rings "1" be-
tween the side plates. Steam
cleaning, high-pressure washes,
certain solvent and kerosene can
damage these O-rings.
4. Inspect:
• O-ring "1" (drive chain)
Damage
→
Replace the drive
chain.
•
Roller "2"
• Side plate "3"
Damage/wear
→
Replace the
drive chain.
5. Check:
• Drive chain stiffness "a"
Clean and oil the drive chain and
hold as illustrated.
Stiff
→
Replace the drive chain.
6. Install:
•
Chain joint "1"
• O-ring "2"
•
Drive chain "3"
• Link plate "4"
Recommended brake flu-
id:
DOT #4
Drive chain length (15
links):
<Limit>: 239.3 mm
(9.42 in)
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