2001 YAMAHA YZ426F height

SPEC

2 - 1
GENERAL SPECIFICATIONS
EC200000
SPECIFICATIONS
EC211000
GENERAL SPECIFICATIONS
Model name: YZ426FLC (EUROPE)
YZ426FN (USA)
YZ426F(N) (CDN, AUS, NZ, ZA)
Model code number: 5JG5 (USA)
5JG6 (EUROPE)
5JG8 (CDN, AUS, NZ, ZA)
Dimensions:
Overall length 2,171 mm (85.5 in)
Overall width 827 mm (32.6 in)
Overall height 1,303 mm (51.3 in)
Seat height 998 mm (39.3 in)
Wheelbase 1,490 mm (58.7 in)
Minimum ground clearance 373 mm (14.7 in)
Basic weight:
With oil and full fuel tank 113.0 kg (249 lb)
Engine:
Engine type Liquid cooled 4-stroke, DOHC
Cylinder arrangement Single cylinder, forward inclined
Displacement 426 cm
3

(15.0 Imp oz, 14.4 US oz)
Bore

´

stroke 95.0
´
60.1 mm (3.74
´
2.37 in)
Compression ratio 12.5 : 1
Starting system Kick starter
Lubrication system: Dry sump
Oil type or grade:
Engine oil (For USA and CDN)
At 5 ˚C (40 ˚F) or higher


Yamalube 4 (20W-40) or SAE 20W-40 type SH
motor oil (Non-Friction modified)
At 15 ˚C (60 ˚F) or lower
õ

Yamalube 4 (10W-30) or SAE 10W-30 type SH
motor oil (Non-Friction modified) and/or
Yamalube 4-R (15W-50 (Non-Friction modified)
(Except for USA and CDN)
API “SH” or higher grade
-20
-4-10
140
3010
5020
6830
8640 50
104
122¡CTemp.
¡F
10W-30
10W-40
20W-40
20W-50
15W-40

2

2

SPEC

2 - 8
MAINTENANCE SPECIFICATIONS
Clutch:
Friction plate thickness 2.9 ~ 3.1 mm (0.114 ~ 0.122 in) 2.7 mm
(0.106 in)
Quantity 9 ----
Clutch plate thickness 1.1 ~ 1.3 mm (0.043 ~ 0.051 in) ----
Quantity 8 ----
Warp limit ---- 0.1 mm
(0.004 in)
Clutch spring free length 50 mm (1.97 in) 49 mm
(1.93 in)
Quantity 6 ----
Clutch housing thrust clearance 0.10 ~ 0.35 mm
(0.0039 ~ 0.0138 in)----
Clutch housing radial clearance 0.010 ~ 0.044 mm
(0.0004 ~ 0.0017 in)----
Clutch release method Inner push, cam push ----
Shifter:
Shifter type Cam drum and guide bar ----
Guide bar bending limit ---- 0.05 mm
(0.002 in)
Kick starter:
Type Ratchet type ----
Carburetor:
I. D. mark 5JG5 50 ----
Main jet (M.J) #162 ----
Main air jet (M.A.J) #200 ----
Jet needle - clip position (J.N) OBEJP-4 ----
Cutaway (C.A) 1.5 ----
Pilot jet (P.J) #42 ----
Pilot air jet (P.A.J) #100 ----
Pilot outlet (P.O) ø0.9 ----
Pilot screw (example) (P.S) 1-1/4 ----
Bypass (B.P) ø1.0 ----
Valve seat size (V.S) ø3.8 ----
Starter jet (G.S) #72 ----
Float height (F.H) 8 mm (0.31 in) ----
Engine idle speed 1,700 ~ 1,900 r/min ----
Intake vacuum29.3 ~ 34.7 kPa (220 ~ 260 mmHg,
8.66 ~ 10.24 inHg)---- Item Standard Limit

SPEC

2 - 9
MAINTENANCE SPECIFICATIONS
Lubrication system:
Oil filter type Wire mesh type ----
Oil pump type Trochoid type ----
Tip clearance “A” 0.12 mm or less
(0.0047 in or less)0.20 mm
(0.008 in)
Tip clearance “B” 0.09 ~ 0.17 mm
(0.0035 ~ 0.0067 in)0.24 mm
(0.009 in)
Side clearance 0.03 ~ 0.10 mm
(0.0012 ~ 0.0039 in)0.17 mm
(0.007 in)
Bypass valve setting pressure 40 ~ 80 kPa (0.4 ~ 0.8 kg/cm
2

,
5.69 ~ 11.38 psi)----
Cooling:
Radiator core size
Width 117.8 mm (4.6 in) ----
Height 260 mm (10.2 in) ----
Thickness 32 mm (1.26 in) ----
Radiator cap opening pressure 110 kPa (1.1 kg/cm
2

, 15.6 psi) ----
Radiator capacity (total) 0.76 L (0.67 lmp qt, 0.80 US qt) ----
Water pump
Type Single-suction centrifugal pump ----Item Standard Limit

SPEC
2 - 14
MAINTENANCE SPECIFICATIONS
Wheel:
Front wheel type Spoke wheel ----
Rear wheel type Spoke wheel ----
Front rim size/material 21 ´ 1.60/Aluminum ----
Rear rim size/material 19 ´ 2.15/Aluminum ----
Rim runout limit:
Radial ---- 2.0 mm (0.08 in)
Lateral ---- 2.0 mm (0.08 in)
Drive chain:
Type/manufacturer DID520DMA2 SDH/DAIDO ----
Number of links 113 links + joint ----
Chain slack 40 ~ 50 mm (1.6 ~ 2.0 in) ----
Chain length (10 links) ----152.5 mm (6.00 in)
Front disc brake:
Disc outside dia. ´ Thickness 250 ´ 3.0 mm (9.84 ´ 0.12 in) 250 ´ 2.5 mm
(9.84 ´ 0.10 in)
Pad thickness 4.4 mm (0.17 in) 1 mm (0.04 in)
Master cylinder inside dia. 11.0 mm (0.433 in) ----
Caliper cylinder inside dia. 27.0 mm (1.063 in) ´ 2 ----
Brake fluid type DOT #4 ----
Rear disc brake:
Disc outside dia. ´ Thickness 240 ´ 4.0 mm (9.45 ´ 0.16 in) 240 ´ 3.5 mm
(9.45 ´ 0.14 in)
Deflection limit ----0.15 mm (0.006 in)
Pad thickness 6.4 mm (0.25 in) 1.0 mm (0.04 in)
Master cylinder inside dia. 12.7 mm (0.500 in) ----
Caliper cylinder inside dia. 27.0 mm (1.063 in) ´ 1 ----
Brake fluid type DOT #4 ----
Brake lever and brake pedal:
Brake lever position 95 mm (3.74 in) ----
Brake pedal height
(vertical height below footrest top)5 mm (0.20 in) ----
Clutch lever free play (at lever pivot) 2 ~ 4 mm (0.08 ~ 0.16 in) ----
Throttle grip free play 3 ~ 5 mm (0.12 ~ 0.20 in) ----Item Standard Limit

3 - 2
INSP
ADJ

MAINTENANCE INTERVALS
SHIFT FORK, SHIFT CAM, GUIDE BAR
Inspect
c
Inspect wear
ROTOR NUT
Retighten
c

c

MUFFLER
Inspect and retighten
Clean
Replace
c

c

c

c
* Whichever comes first
CRANK
Inspect and clean
c

c

CARBURETOR
Inspect, adjust and clean
c

c
When using a high-pres-
sure washer, make sure
that water does not enter
the accelerator pump.
SPARK PLUG
Inspect and clean
Replace
c

c

c

DRIVE CHAIN
Lubricate, slack, alignment
Replace
c

c

c
Use chain lube
Chain slack: 40 ~ 50 mm
(1.6 ~ 2.0 in)
COOLING SYSTEM
Check coolant level and leakage
Check radiator cap operation
Replace coolant
Inspect hoses
c

c

c

c

c
Every two years
OUTSIDE NUTS AND BOLTS
Retighten
c

c
Refer to “STARTING
AND BREAK-IN” section
in the CHAPTER 1.
AIR FILTER
Clean and lubricate
Replace
c

c

c
Use foam air-filter oil
OIL STRAINER (frame)
Clean
c

FRAME
Clean and inspect
c

c

FUEL TANK, COCK
Clean and inspect
c

c

BRAKES
Adjust lever position and pedal height
Lubricate pivot point
Check brake disc surface
Check fluid level and leakage
Retighten brake disc bolts, caliper
bolts, master cylinder bolts and union
bolts
Replace pads
Replace brake fluid
c

c

c

c

c

c

c

c

c

c

c

c
Every one year
FRONT FORKS
Inspect and adjust
Replace oil
Replace oil seal
c

c

c

c

c
Suspension oil “01”
FRONT FORK OIL SEAL AND DUST
SEAL
Clean and lube
c

c
Lithium base grease ItemAfter
break-inEvery
race
Every
third
(or
500 km)Every
fifth
(or
1,000 km)
As re-
quiredRemarks


3

3 - 26
INSP
ADJREAR BRAKE ADJUSTMENT/
FRONT BRAKE PAD INSPECTION AND REPLACEMENT
EC364002
REAR BRAKE ADJUSTMENT
1. Check:
lBrake pedal height a
Out of specification ® Adjust.
Brake pedal height a:
5 mm (0.20 in)
2. Adjust:
lBrake pedal height
Pedal height adjustment steps:
lLoosen the locknut 1.
lTurn the adjusting nut 2 until the pedal
height a is within specified height.
lTighten the locknut.
WARNING
lAdjust the pedal height between the
maximum and the minimum õ as
shown. (In this adjustment the bolt 3
end b should protrude out of the lower
adjusting nut 4 but not be less than
2 mm (0.08 in) c away from the brake
pedal 5).
lAfter the pedal height adjustment, make
sure that the rear brake does not drag.

õ
EC365080
FRONT BRAKE PAD INSPECTION AND
REPLACEMENT
1. Inspect:
lBrake pad thickness a
Out of specification ® Replace as a
set.
2. Replace:
lBrake pad
Brake pad thickness a:
Standard
4.4 mm (0.17 in) 1.0 mm (0.04 in)
Brake pad replacement steps:
lRemove the pad pin plug 1.

4 - 12
ENGCARBURETOR
EC464511
Float height
1. Measure:
lFloat height a
Out of specification ® Adjust.
Float height:
8.0 mm (0.31 in)
Measurement and adjustment steps:
lHold the carburetor in an upside down
position.
NOTE:
lSlowly tilt the carburetor in the opposite
direction, then take the measurement
when the needle valve aligns with the float
arm.
lIf the carburetor is level, the weight of the
float will push in the needle valve, result-
ing in an incorrect measurement.
lMeasure the distance between the mating
surface of the float chamber and top of the
float using a vernier calipers.
NOTE:
The float arm should be resting on the nee-
dle valve, but not compressing the needle
valve.
lIf the float height is not within specifica-
tion, inspect the valve seat and needle
valve.
lIf either is worn, replace them both.
lIf both are fine, adjust the float height by
bending the float tab b on the float.
lRecheck the float height.
EC464600
Float
1. Inspect:
lFloat 1
Damage ® Replace.

5 - 23
CHASFRONT BRAKE AND REAR BRAKE
4. Install:
lPin 1
lPlain washer 2
lCotter pin 3
NOTE:
After installing, check the brake pedal height.
Refer to “REAR BRAKE ADJUSTMENT” sec-
tion in the CHAPTER 3.
New
Front brake hose
1. Install:
lBrake hose 1
To brake hose holder 2.
NOTE:
Before tightening the bolt (brake hose holder),
pass the brake hose in front of the axle boss
a, then fit it into the hose groove b so that the
brake hose does not contact the nut (wheel
axle).
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
2. Install:
lHose cover 1
lPlain washer 2
lBolt [hose cover (M8)] 3
lBolt [hose cover (M6)] 4
T R..16 Nm (1.6 m · kg, 11 ft · lb)
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
3. Pass the brake hose through the cable
guide 1, then through the guide a on
the protector 2.