Yamaha YZ450FY 2009 Owner's Service Manual page 89

• 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 performance.
• Be sure that water or other contaminants
do not enter master cylinder when refill-
ing.
• Clean up spilled fluid immediately 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 sprock-
et and drive chain as a set.
CHECKING THE DRIVE CHAIN
1. Measure:
• Drive chain length (15 links) "a"
Out of specification → Replace.
Drive chain length (15 links):
<Limit>: 242.9 mm (9.563 in)
• While measuring the drive chain length, push
down on the drive chain to increase its ten-
sion.
• Measure the length between drive chain roller
"1" and "16" as shown.
• Perform this measurement at two or three dif-
ferent places.
2. Remove:
• Master link clip
• Joint "1"
• Drive chain "2"
3. Clean:
• Drive chain
Place it in kerosene, and brush off as much
dirt as possible. Then remove the drive
chain from the kerosene and dry the drive
chain.
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CHASSIS