Yamaha YZ450FX 2021, Owner'S Service Manual

Page: 77 / 374

MAINTENANCE INTERVALS
3-1
EAM20157
MAINTENANCE INTERVALS
EAM30369
MAINTENANCE INTERVALS
NOTICE
ECA25871
• After a break-in or before each race, always check the points shown in “TORQUE-CHECK
POINTS” for tightening torques and retighten them.
• Periodic inspection is essential in making full use of the machine performance. The life of
parts varies significantly according to the environment in which the machine runs (e.g., rain,
dirt, etc.). Therefore, earlier inspection is required by reference to the list below.
TIP
Items marked with an asterisk should be performed by a Yamaha dealer as they require special tools,
data and technical skills.
No. Item Routine
After
break-in
Every race
(about
2.5 hours)
Every third
race (about
7.5 hours)
Every fifth
race (about
12.5 hours)
As required
1 * Valve
• Check the valve clearances.
 
• Check the valve seats and the
valve faces for wear.

• Replace.

2 * Valve spring
• Check the free length.

• Replace.

3 * Valve lifter
• Check for scratches and wear.

• Replace.

4 * Camshaft
• Inspect the camshaft surface.
• Inspect the decompression sys-
tem.

• Replace.

5 * Timing chain
• Check for damage and sticking.

• Replace.
 
6 * Timing chain ten-
sioner
• Replace.
 
7 * Camshaft sprocket
• Check for wear on the teeth and
for damage.

• Replace.

8 * Piston
• Inspect crack.

• Inspect carbon deposits and elim-
inate them.

• Replace the piston, piston pin,
piston pin clip, and piston ring all
as a set.
 
9 * Piston ring
• Check the end gap of the piston
ring.

• Replace the piston, piston pin,
piston pin clip, and piston ring all
as a set.
 
10 * Piston pin
• Inspect.

• Replace the piston, piston pin,
piston pin clip, and piston ring all
as a set.
 