Yamaha YZ450FX 2021 Owner's Service Manual page 205

Bolt (timing chain tensioner)
10 N·m (1.0 kgf·m, 7.4 lb·ft)
a a
1 1
4 4
c. Release the screwdriver, check that the
tensioner rod comes out smoothly, and
tighten the gasket "5" and the cap bolt "6".
Tensioner cap bolt
6 N·m (0.6 kgf·m, 4.4 lb·ft)
3. Turn:
• Crankshaft
Counterclockwise several turns.
4. Check:
• Top dead center (TDC) mark on the genera-
tor rotor
Align with the crankcase alignment mark.
• Camshaft match marks
Align with the cylinder head surface.
Out of alignment  Adjust.
5. Install:
• Timing chain guide (top side) "1"
• Cylinder head cover gasket "2"
• Gasket (spark plug hole) "3"
• Cylinder head cover "4"
• Bolt (cylinder head cover) "5"
Bolt (cylinder head cover)
10 N·m (1.0 kgf·m, 7.4 lb·ft)
TIP
Before installation, apply the sealant to the cylin-
3 3
4 4
2 2 2
5 5
6 6
New
New
5-19
der head cover gasket.
Yamaha bond No. 1215
90890-85505
Three bond No. 1215®
5
4
3
6. Install:
• Cylinder head breather hose
• Spark plug
Spark plug
13 N·m (1.3 kgf·m, 9.6 lb·ft)
CAMSHAFT
5
1
2