Yamaha YZ450FY 2009 Owner's Service Manual page 90

4. Check:
• Drive chain stiffness "a"
Clean and oil the drive chain and hold as il-
lustrated.
Stiff → Replace the drive chain.
5. Install:
• Drive chain "1"
• Joint "2"
• Master link clip "3"
Be sure to install the master link clip to the
direction as shown.
a. Turning direction
6. Lubricate:
• Drive chain
Drive chain lubricant:
SAE 10W-30 motor oil or suitable
chain lubricants
ADJUSTING THE DRIVE CHAIN SLACK
1. Elevate the rear wheel by placing the suit-
able stand under the engine.
2. Check:
• Drive chain slack "a"
Above the seal guard installation bolt.
Out of specification → Adjust.
Drive chain slack:
50–60 mm (2.0–2.4 in)
Before checking and/or adjusting, rotate the
rear wheel through several revolutions and
check the slack several times to find the tightest
point. Check and/or adjust the drive chain slack
with the rear wheel in this "tight chain" position.
3. Adjust:
• Drive chain slack
Drive chain slack adjustment steps:
a. Loosen the axle nut "1" and locknuts "2".
b. Adjust the drive chain slack by turning the
adjusters "3".
To tighten → Turn the adjuster "3" counter-
clockwise.
To loosen → Turn the adjuster "3" clock-
wise and push wheel forward.
c. Turn each adjuster exactly the same amount
to maintain correct axle alignment. (There
are marks "a" on each side of the drive chain
puller alignment.) NOTICE: Improper drive
chain slack will overload the engine
aswell as other vital parts of the motorcy-
cle and can lead to chain slippage or
breakage. To prevent this from occur-
ring, keep the drive chain slack within the
specified limits.
3-25
CHASSIS