2001 YAMAHA YZ426F lock

ILLUSTRATED SYMBOLS
(Refer to the illustration)
Illustrated symbols
1
to
7
are designed as
thumb tabs to indicate the chapter’s number
and content.
1
General information
2
Specifications
3
Regular inspection and adjustments
4
Engine
5
Chassis
6
Electrical
7
Tuning
Illustrated symbols
8
to
D
are used to identify
the specifications appearing in the text.
8
With engine mounted
9
Special tool
0
Filling fluid
A
Lubricant
B
Tightening
C
Specified value, Service limit
D
Resistance (
W
), Voltage (V), Electric current (A)
Illustrated symbols
E
to
H
in the exploded
diagrams indicate grade of lubricant and loca-
tion of lubrication point.
E
Apply engine oil
F
Apply molybdenum disulfide oil
G
Apply lightweight lithium-soap base grease
H
Apply molybdenum disulfide grease
Illustrated symbols
I
to
J in the exploded
diagrams indicate where to apply a locking
agent and where to install new parts.
IApply locking agent (LOCTITE®)
JUse new one 12
34
56
78
90
AB
CD
EF
GH
IJ
GEN
INFOSPEC
INSP
ADJENG
CHAS–+ELEC
TUN
T R..
EM
BM
New

1 - 4
GEN
INFO

IMPORTANT INFORMATION
EC132000
ALL REPLACEMENT PARTS
1. We recommend to use Yamaha genuine
parts for all replacements. Use oil and/or
grease recommended by Yamaha for
assembly and adjustment.
EC133000
GASKETS, OIL SEALS AND O-RINGS
1. All gaskets, oil seals, and O-rings should
be replaced when an engine is over-
hauled. All gasket surfaces, oil seal lips,
and O-rings must be cleaned.
2. Properly oil all mating parts and bearings
during reassembly. Apply grease to the
oil seal lips.
EC134000
LOCK WASHERS/PLATES AND COTTER
PINS
1. All lock washers/plates
1
and cotter pins
must be replaced when they are
removed. Lock tab(s) should be bent
along the bolt or nut flat(s) after the bolt
or nut has been properly tightened.
EC135001
BEARINGS AND OIL SEALS
1. Install the bearing(s)
1
and oil seal(s)
2
with their manufacturer’s marks or num-
bers facing outward. (In other words, the
stamped letters must be on the side
exposed to view.) When installing oil
seal(s), apply a light coating of light-
weight lithium base grease to the seal
lip(s). Oil the bearings liberally when
installing.
CAUTION:

Do not use compressed air to spin the
bearings dry. This causes damage to the
bearing surfaces.

1 - 19
GEN
INFO
CLEANING AND STORAGE
EC1B0000
CLEANING AND STORAGE
EC1B1000
CLEANING
Frequent cleaning of your machine will
enhance its appearance, maintain good over-
all performance, and extend the life of many
components.
1. Before washing the machine, block off
the end of the exhaust pipe to prevent
water from entering. A plastic bag
secured with a rubber band may be used
for this purpose.
2. If the engine is excessively greasy, apply
some degreaser to it with a paint brush.
Do not apply degreaser to the chain,
sprockets, or wheel axles.
3. Rinse the dirt and degreaser off with a
garden hose; use only enough pressure
to do the job.
CAUTION:
Excessive hose pressure may cause water
seepage and contamination of wheel bear-
ings, front forks, brakes and transmission
seals. Many expensive repair bills have
resulted from improper high pressure
detergent applications such as those avail-
able in coin-operated car washers.
4. After the majority of the dirt has been
hosed off, wash all surfaces with warm
water and a mild detergent. Use an old
toothbrush to clean hard-to-reach places.
5. Rinse the machine off immediately with
clean water, and dry all surfaces with a
soft towel or cloth.
6. Immediately after washing, remove
excess water from the chain with a paper
towel and lubricate the chain to prevent
rust.
7. Clean the seat with a vinyl upholstery
cleaner to keep the cover pliable and
glossy.

1 - 20
GEN
INFO
CLEANING AND STORAGE
8. Automotive wax may be applied to all
painted or chromed surfaces. Avoid com-
bination cleaner-waxes, as they may con-
tain abrasives.
9. After completing the above, start the
engine and allow it to idle for several min-
utes.
EC1B2001
STORAGE
If your machine is to be stored for 60 days or
more, some preventive measures must be
taken to avoid deterioration. After cleaning the
machine thoroughly, prepare it for storage as
follows:
1. Drain the fuel tank, fuel lines, and the
carburetor float bowl.
2. Remove the spark plug, pour a table-
spoon of SAE 10W-30 motor oil in the
spark plug hole, and reinstall the plug.
With the engine stop switch pushed in,
kick the engine over several times to coat
the cylinder walls with oil.
3. Remove the drive chain, clean it thor-
oughly with solvent, and lubricate it.
Reinstall the chain or store it in a plastic
bag tied to the frame.
4. Lubricate all control cables.
5. Block the frame up to raise the wheels off
the ground.
6. Tie a plastic bag over the exhaust pipe
outlet to prevent moisture from entering.
7. If the machine is to be stored in a humid
or salt-air environment, coat all exposed
metal surfaces with a film of light oil. Do
not apply oil to rubber parts or the seat
cover.
NOTE:
Make any necessary repairs before the
machine is stored.

SPEC

2 - 6
MAINTENANCE SPECIFICATIONS
Valve seat width IN 0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in)1.6 mm
(0.0630 in)
EX 0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in)1.6 mm
(0.0630 in)
Valve spring:
Free length IN 41.36 mm (1.63 in) 39.3 mm
(1.55 in)
EX 43.60 mm (1.72 in) 41.4 mm
(1.63 in)
Set length (valve closed) IN 32.87 mm (1.29 in) ----
EX 35.38 mm (1.39 in) ----
Compressed pressure
(installed) IN 112.8 ~ 129.8 N
(11.5 ~ 13.2 kg, 25.35 ~ 29.10 lb)----
EX 116.3 ~ 133.9 N
(11.9 ~ 13.7 kg, 26.23 ~ 30.20 lb)----
Tilt limit IN ----2.5˚/ 1.8 mm
(2.5˚/0.071 in)
EX ----2.5˚/1.9 mm
(2.5˚/0.075 in)
Direction of winding
(top view) IN Clockwise ----
EX Clockwise ----
Piston:
Piston to cylinder clearance 0.040 ~ 0.065 mm
(0.0016 ~ 0.0026 in)0.1 mm
(0.004 in)
Piston size “D” 94.945 ~ 94.960 mm
(3.738 ~ 3.739 in)----
Measuring point “H” 9 mm (0.354 in) ----
Piston off-set 1 mm (0.0394 in) ----
Piston pin bore inside diameter 19.004 ~ 19.015 mm
(0.7482 ~ 0.7486 in)19.045 mm
(0.7498 in)
Piston pin outside diameter 18.991 ~ 19.000 mm
(0.7477 ~ 0.7480 in)18.971 mm
(0.7469 in) Item Standard Limit
*
H
D

SPEC
2 - 15
MAINTENANCE SPECIFICATIONS
NOTE:
1. First, tighten the ring nut approximately 38 Nm (3.8 m • kg, 27 ft • lb) by using the ring nut
wrench, then loosen the ring nut one turn.
2. Retighten the ring nut 7 Nm (0.7 m • kg, 5.1 ft • lb).Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Handle crown and outer tube M8 ´ 1.25 4 23 2.3 17
Under bracket and outer tube M8 ´ 1.25 4 20 2.0 14
Handle crown and steering shaft M24 ´ 1.0 1 145 14.5 105
Handlebar holder (upper) M8 ´ 1.25 4 28 2.8 20
Steering ring nut M28 ´ 1.0 1 Refer to NOTE.
Front fork and cap bolt M48 ´ 1.0 2 30 3.0 22
Front fork and base valve M30 ´ 1.0 2 55 5.5 40
Cap bolt and damper rod (front fork) M12 ´ 1.25 2 29 2.9 21
Bleed screw (front fork) and cap bolt M5 ´ 0.8 2 1 0.1 0.7
Front fork and protector M6 ´ 1.0 6 10 1.0 7.2
Front fork and brake hose holder M6 ´ 1.0 2 10 1.0 7.2
Front fork and hose cover M8 ´ 1.25 1 16 1.6 11
Front fork and hose cover M6 ´ 1.0 1 7 0.7 5.1
Throttle cable cap M5 ´ 0.8 2 4 0.4 2.9
Clutch lever holder M5 ´ 0.8 2 4 0.4 2.9
Decompression lever holder M5 ´ 0.8 2 4 0.4 2.9
Front brake master cylinder and bracket M6 ´ 1.0 2 9 0.9 6.5
Front brake master cylinder cap M4 ´ 0.7 2 2 0.2 1.4
Brake lever mounting (bolt) M6 ´ 1.0 1 6 0.6 4.3
Brake lever mounting (nut) M6 ´ 1.0 1 6 0.6 4.3
Brake lever position locknut M6 ´ 1.0 1 5 0.5 3.6
Cable guide (front brake hose) and guide stay M5 ´ 0.8 1 4 0.4 2.9
Front brake hose union bolt (master cylinder) M10 ´ 1.25 1 30 3.0 22
Front brake hose union bolt (caliper) M10 ´ 1.25 1 30 3.0 22
Front brake caliper and front fork M8 ´ 1.25 2 23 2.3 17
Brake caliper (front and rear) and pad pin plug M10 ´ 1.0 1 3 0.3 2.2
Brake caliper (front and rear) and pad pin M10 ´ 1.0 1 18 1.8 13
Brake caliper (front and rear) and bleed screw M8 ´ 1.25 1 6 0.6 4.3
Front wheel axle and nut M16 ´ 1.5 1 105 10.5 75
Front wheel axle holder M8 ´ 1.25 4 23 2.3 17
Front brake disc and wheel hub M6 ´ 1.0 6 12 1.2 8.7
Rear brake disc and wheel hub M6 ´ 1.0 6 14 1.4 10
Brake pedal mounting M8 ´ 1.25 1 26 2.6 19
Rear brake master cylinder and frame M6 ´ 1.0 2 10 1.0 7.2

2 - 21
SPEC

CABLE ROUTING DIAGRAM
EC240000
CABLE ROUTING DIAGRAM
1
Hose guide
2
Brake hose
3
Fuel tank breather hose
4
Oil tank breather hose
5
Clamp
6
“ENGINE STOP” button lead
7
Sub wire harness
8
TPS (throttle position
sensor) lead
9
Neutral switch lead
0
Oil hose
A
Hose holder
B
CDI magneto lead
C
Clutch cable
D
Cylinder head breather hose
E
Carburetor breather hose
F
Overflow hose

Pass the clutch cable through
the cable guide.
õ
Pass the fuel tank breather hose
between the handlebar and ten-
sion bar, then insert its end into
the hole of the number plate.
‚
Pass the decompression cable
and “ENGINE STOP” button
lead under the frame.
ë
Fasten the CDI magneto lead,
neutral switch lead and
“ENGINE STOP” button lead to
the frame with a plastic locking
tie and cut off the tie end.
ä
Pass the “ENGINE STOP” but-
ton lead along the inner side of
the oil tank breather hose.
ì
Fasten the sub wire harness
and “ENGINE STOP” button
lead to the frame in front of the
protector of the sub wire har-
ness with a plastic locking tie
and cut off the tie end.
í
Pass the cylinder head breather
hose along the right side of the
oil tank breather hose.
î
Pass the sub wire harness
between the engine brackets.
é
Fasten the sub wire harness
and “ENGINE STOP” button
lead to the frame at the rear of
the protector of the sub wire har-
ness with a plastic locking tie
and cut off the tie end.

2 - 22
SPEC

CABLE ROUTING DIAGRAM
ï
Fasten the TPS lead (in the
sub wire harness) under the
frame so that it does not con-
tact the carburetor.
ð
Fasten the TPS lead under the
coupler to the frame with a
plastic locking tie.
ñ
Pass the carburetor breather
hose and overflow hose
between the connecting rod
and cross tube (frame).
÷
Fasten the neutral switch lead
and oil hose together with a
plastic locking tie and cut off
the tie end.
ö
Fasten the cylinder head
breather hose and neutral
switch lead to the frame with a
plastic locking tie.
¯
Fasten the neutral switch lead
to the frame with a plastic
band.
¸
Fasten the cylinder head
breather hose with the hose
holder.
Î
Pass the clutch cable through
the cable guide.
å
Fasten the neutral switch lead
and CDI magneto lead together
with a plastic band.
ê
Pass the clutch cable on the
inside the cylinder head
breather hose.
æ
Pass the cylinder head
breather hose along the inner
side of the radiator pipe.
è
Pass the radiator breather
hose from the right side of the
frame to the left side, over radi-
ator pipe 1, along the inner side
of radiator hose 4 and the radi-
ator, and between the lower
engine bracket, crankcase, oil
hose and the frame.
×Pass the clutch cable between
the frame and radiator and
over the lower boss on the radi-
ator.