Yamaha YZ125 2019 Owner's Service Manual page 114

5. Install:
• Gasket (power valve housing)
• Power valve housing "1"
• Bolt (power valve housing) "2"
Bolt (power valve housing):
4 Nm (0.4 m•kg, 2.9 ft•lb)
6. Install:
• O-ring "1"
Apply the lithium soap base grease on the O-
rings.
7. Install:
• Cylinder head "1"
• Copper washer "2"
• Nut (cylinder head) "3"
Nut (cylinder head):
28 Nm (2.8 m•kg, 20 ft•lb)
Tighten the nuts (cylinder head) in stage, using
a crisscross pattern.
CYLINDER HEAD, CYLINDER AND PISTON
8. Install:
• Engine bracket "1"
• Bolt (engine bracket) "2"
• Engine mounting bolt (upper) "3"
9. Install:
• Spark plug "1"
• Spark plug cap "2"
4-27
Bolt (engine bracket):
34 Nm (3.4 m•kg, 24 ft•lb)
Engine mounting bolt (upper):
34 Nm (3.4 m•kg, 24 ft•lb)
Spark plug:
20 Nm (2.0 m•kg, 14 ft•lb)