2000 YAMAHA YZ426F Owners Manual

SPEC

2 - 4
MAINTENANCE SPECIFICATIONS
MAINTENANCE SPECIFICATIONS
ENGINE
Item Standard Limit
Cylinder head:
Warp limit ---- 0.05 mm
(0.002 in)
Cylinder:
Bore size95.00 ~ 95.01 mm
(3.7402 ~ 3.7406 in)----
Out of round limit ---- 0.05 mm
(0.002 in)
Camshaft:
Drive method Chain drive (Left) ----
Cam cap inside diameter 22.000 ~ 22.021 mm
(0.8661 ~ 0.8670 in)----
Camshaft outside diameter 21.967 ~ 21.980 mm
(0.8648 ~ 0.8654 in)----
Shaft-to-cap clearance 0.020 ~ 0.054 mm
(0.0008 ~ 0.0021 in)----
Cam dimensions
Intake “A” 31.7 ~ 31.8 mm
(1.248 ~ 1.252 in)31.6 mm
(1.244 in)
“B” 22.95 ~ 23.05 mm
(0.9035 ~ 0.9075 in)22.85 mm
(0.900 in)
“C” 8.65 ~ 8.85 mm
(0.3406 ~ 0.3484 in)----
Exhaust “A” 31.2 ~ 31.3 mm
(1.2283 ~ 1.2323 in)31.1 mm
(1.224 in)
“B” 22.95 ~ 23.05 mm
(0.9035 ~ 0.9075 in)22.85 mm
(0.900 in)
“C” 8.15 ~ 8.35 mm
(0.3209 ~ 0.3287 in)----
C
A
B

SPEC

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MAINTENANCE SPECIFICATIONS
Camshaft runout limit ---- 0.03 mm
(0.0012 in)
Cam chain:
Cam chain type/No. of links 92RH2010-120MPX/120 ----
Cam chain adjustment method Automatic ----
Valve, valve seat, valve guide:
Valve clearance (cold) IN 0.15 ~ 0.20 mm
(0.0059 ~ 0.0079 in)----
EX 0.25 ~ 0.30 mm
(0.0098 ~ 0.0118 in)----
Valve dimensions:
“A” head diameter IN 26.9 ~ 27.1 mm
(1.0591 ~ 1.0669 in)----
EX 27.9 ~ 28.1 mm
(1.0984 ~ 1.1063 in)----
“B” face width IN 2.26 mm (0.089 in) ----
EX 2.26 mm (0.089 in) ----
“C” seat width IN0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in)1.5 mm
(0.0591 in)
EX 0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in)1.5 mm
(0.0591 in)
“D” margin thickness IN 1 mm (0.0394 in) 0.85 mm
(0.033 in)
EX 1 mm (0.0394 in) 0.85 mm
(0.033 in)
Stem outside diameter IN4.475 ~ 4.490 mm
(0.1762 ~ 0.1768 in)----
EX 4.960 ~ 4.975 mm
(0.1953 ~ 0.1959 in)----
Guide inside diameter IN 4.500 ~ 4.512 mm
(0.1772 ~ 0.1776 in)----
EX 5.000 ~ 5.012 mm
(0.1969 ~ 0.1973 in)----
Stem-to-guide clearance IN0.010 ~ 0.037 mm
(0.0004 ~ 0.0015 in)0.08 mm
(0.003 in)
EX 0.025 ~ 0.052 mm
(0.0010 ~ 0.0020 in)0.10 mm
(0.004 in) Item Standard Limit
Head Diameter
B
Face WidthC
Seat Width
D
Margin ThicknessA

SPEC

2 - 6
MAINTENANCE SPECIFICATIONS
Stem runout limit ---- 0.01 mm
(0.0004 in)
Valve seat width IN0.9 ~ 1.1 mm (0.0354 ~ 0.0433 in)----
EX 0.9 ~ 1.1 mm (0.0354 ~ 0.0433 in)----
Valve spring:
Free length IN 39.42 mm (1.55 in) 37.5 mm
(1.48 in)
EX 41.80 mm (1.65 in) 39.8 mm
(1.57 in)
Set length (valve closed) IN 32.87 mm (1.29 in) ----
EX 35.35 mm (1.39 in) ----
Compressed pressure
(installed) IN 124 ~ 136 N
(12.6 ~ 13.8 kg, 27.78 ~ 30.42 lb)----
EX 123 ~ 143 N
(12.6 ~ 14.6 kg, 27.78 ~ 32.19 lb)----
Tilt limit IN ----2.5˚/ 1.7 mm
(2.5˚/0.067 in)
EX ----2.5˚/1.8 mm
(2.5˚/0.071 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) ----Item Standard Limit
*
H
D

SPEC

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MAINTENANCE SPECIFICATIONS
Piston pin bore inside diameter19.004 ~ 19.015 mm
(0.7482 ~ 0.7486 in)19.045 mm
(0.7498 in)
Piston pin outside diameter18.991 ~ 19.000 mm
(0.7477 ~ 0.7480 in)18.971 mm
(0.7469 in)
Piston rings:
Top ring:
Type Barrel ----
Dimensions (B

´

T) 1.2
´
3.5 mm (0.05
´
0.14 in) ----
End gap (installed) 0.20 ~ 0.30 mm
(0.008 ~ 0.012 in)0.55 mm
(0.022 in)
Side clearance (installed) 0.030 ~ 0.065 mm
(0.0012 ~ 0.0026 in)0.13 mm
(0.005 in)
2nd ring:
Type Taper ----
Dimensions (B

´

T) 1.00
´
3.35 mm (0.04
´
0.13 in) ----
End gap (installed) 0.35 ~ 0.50 mm
(0.014 ~ 0.020 in)0.85 mm
(0.033 in)
Side clearance 0.020 ~ 0.055 mm
(0.0008 ~ 0.0022 in)0.13 mm
(0.005 in)
Oil ring:
Dimensions (B

´

T) 2.0
´
2.9 mm (0.08
´
0.11 in) ----
End gap (installed) 0.2 ~ 0.5 mm (0.01 ~ 0.02 in) ----
Crankshaft:
Crank width “A” 61.95 ~ 62.00 mm
(2.439 ~ 2.441 in)----
Runout limit “C” 0.03 mm (0.0012 in) 0.05 mm
(0.002 in)
Big end side clearance “D” 0.15 ~ 0.45 mm
(0.0059 ~ 0.0177 in)0.50 mm
(0.02 in)
Small end free play “F” 0.4 ~ 1.0 mm (0.02 ~ 0.04 in) 2.0 mm
(0.08 in)
Balancer:
Balancer drive method Gear ----
Decompression device:
Type Manual ----
Cable free play 5 ~ 9 mm (0.20 ~ 0.35 in)
Air filter oil grade: Engine oil ----Item Standard Limit
T
B
B
T
B
T

SPEC

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MAINTENANCE SPECIFICATIONS
Clutch:
Friction plate thickness 2.9 ~ 3.1 mm
(0.114 ~ 0.122 in)2.7 mm
(0.11 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 44 mm (1.73 in) 43 mm
(1.69 in)
Quantity 6 ----
Clutch housing thrust clearance 0.20 ~ 0.45 mm
(0.0079 ~ 0.0177 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:
USAEUROPE, CDN,
ZA, AUS, NZ
I. D. mark 5JG1 00 5JG2 10 ----
Main jet (M.J) #162
¬
----
Main air jet (M.A.J) #200
¬
----
Jet needle (J.N) OBEKR-4 OBEKQ-4 ----
Cutaway (C.A) 15
¬
----
Pilot air jet 1 (P.A.J.1) #100
¬
----
Pilot outlet (P.O) 0.9
¬
----
Pilot jet (P.J) #42
¬
----
Pilot screw (example) (P.S) 1-3/4 1-1/2 ----
Bypass 1 (B.P.1) 1.0
¬
----
Valve seat size (V.S) 3.8
¬
----
Starter jet 1 (G.S.1) #72
¬
----
Float height (F.H) 8 mm (0.31 in)
¬
----
Engine idle speed 1,700 ~
1,900 r/min
¬
----
Intake vacuum29.3 ~ 32.0 kPa
(220 ~ 240 mmHg,
8.66 ~ 9.45 inHg)
¬
---- Item Standard Limit

SPEC

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MAINTENANCE SPECIFICATIONS
Lubrication system:
Oil filter type Wire mesh type ----
Oil pump type Trochoid type ----
Tip clearance “A” or “B” 0.07 ~ 0.12 mm
(0.0028 ~ 0.0047 in)0.15 mm
(0.006 in)
Side clearance 0.03 ~ 0.08 mm
(0.0012 ~ 0.0031 in)0.15 mm
(0.006 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 pressure110 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

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MAINTENANCE SPECIFICATIONS
Item Standard
Lubrication chart:
Pressure feed
Splashed scavenge
Oil strainer
Oil pan Oil pump rotor 2
Oil pump rotor 1
Oil tank
Oil filter
Check ball
Cylinder head
Crank pinPiston pinPiston
Drive axleMain axleTransmission gears
Camshaft
Valve lifter

SPEC

2 - 11
MAINTENANCE SPECIFICATIONS
Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Spark plug M10
´
1.0 1 13 1.3 9.4
Camshaft cap M6
´
1.0 10 10 1.0 7.2
Cylinder head (stud bolt) M6
´
1.0 2 7 0.7 5.1
M8
´
1.25 3 15 1.5 11
(bolt) M10
´
1.25 4 44 4.4 32
(nut) M6
´
1.0 2 10 1.0 7.2
M8
´
1.25 2 20 2.0 14
Cylinder head cover M6
´
1.0 2 10 1.0 7.2
Cylinder M6
´
1.0 1 10 1.0 7.2
Timing chain tensioner M6
´
1.0 2 10 1.0 7.2
Tensioner cap bolt M6
´
1.0 1 7 0.7 5.1
Timing chain guide (rear) M6
´
1.0 2 10 1.0 7.2
Decompression shaft M6
´
1.0 1 7 0.7 5.1
Decompression cable guide M6
´
1.0 1 10 1.0 7.2
Exhaust pipe (nut) M8
´
1.25 1 24 2.4 17
(bolt) M8
´
1.25 1 24 2.4 17
Silencer M8
´
1.25 2 35 3.5 25
Silencer clamp M8
´
1.25 1 20 2.0 14
Exhaust pipe protector M6
´
1.0 3 10 1.0 7.2
Clamp (air cleaner joint) M5
´
0.8 1 3 0.3 2.2
Clamp (carburetor joint) M4
´
0.7 1 3 0.3 2.2
Air filter joint clamp M6
´
1.0 1 3 0.3 2.2
Throttle cable cover M5
´
0.8 1 4 0.4 2.9
Air filter element M6
´
1.0 1 2 0.2 1.4
Radiator panel (upper) M6
´
1.0 2 10 1.0 7.2
Radiator M6
´
1.0 6 10 1.0 7.2
Radiator hose clamp M6
´
1.0 8 2 0.2 1.4
Impeller M8 ´ 1.25 1 14 1.4 10
Water pump housing cover M6 ´ 1.0 3 10 1.0 7.2
Coolant drain bolt M6 ´ 1.0 1 10 1.0 7.2
Oil pump cover M5 ´ 0.8 1 4 0.4 2.9
Oil pump M6 ´ 1.0 3 10 1.0 7.2
Engine oil drain bolt (oil filter) M6 ´ 1.0 1 10 1.0 7.2
Oil filter cover M6 ´ 1.0 2 10 1.0 7.2
Oil delivery pipe 1 M10 ´ 1.25 1 20 2.0 14
M8 ´ 1.25 2 18 1.8 13
Oil hose clamp – 2 2 0.2 1.4
Clutch cover M6 ´ 1.0 7 10 1.0 7.2
Crankcase cover (right) M6 ´ 1.0 10 10 1.0 7.2
Crankcase cover (left) M6 ´ 1.0 8 10 1.0 7.2
Crankcase M6 ´ 1.0 12 12 1.2 8.7
Oil drain bolt (crankcase) M12 ´ 1.5 1 20 2.0 1.4
Oil drain bolt (frame) M8 ´ 1.25 1 23 2.3 17