Yamaha YZ450FP 2023 Owner's Service Manual page 193

3-27.
Drive chain slack (Maintenance
Stand)
50.0–60.0 mm (1.97–2.36 in)
ECA24590
NOTICE
A drive chain that is too tight will overload
the engine and other vital parts, and one that
is too loose can skip and damage the swing-
arm or cause an accident. Therefore, keep
the drive chain slack within the specified lim-
its.
4-77
CHAIN DRIVE