2002 YAMAHA YZ426F engine oil

SPEC

2 - 2
GENERAL SPECIFICATIONS
Oil capacity:
Engine oil
Periodic oil change 1.3 L (1.14 Imp qt, 1.37 US qt)
With oil filter replacement 1.4 L (1.23 Imp qt, 1.48 US qt)
Total amount 1.5 L (1.32 Imp qt, 1.59 US qt)
Coolant capacity (including all routes): 1.2 L (1.06 Imp qt, 1.27 US qt)
Air filter: Wet type element
Fuel:
Type Premium unleaded gasoline only with a research
octane number of 95 or higher.(Except for ZA)
Premium gasoline (For ZA)
Tank capacity 8.0 L (1.76 Imp gal, 2.11 US gal)
Carburetor:
Type FCR MX39
Manufacturer KEIHIN
Spark plug:
Type/manufacturer CR8E/NGK
U24ESR-N/DENSO
Gap 0.7 ~ 0.8 mm (0.028 ~ 0.031 in)
Clutch type: Wet, multiple-disc
Transmission: USA, CDN, ZA,
AUS, NZEUROPE
Primary reduction system Gear
←
Primary reduction ratio 62/21 (2.952)
←
Secondary reduction system Chain drive
←
Secondary reduction ratio 49/14 (3.500) 48/14 (3.429)
Transmission type Constant mesh,
5-speed
←
Operation Left foot operation
←
Gear ratio: 1st 24/13 (1.846)
←
2nd 23/15 (1.533)
←
3rd 23/18 (1.278)
←
4th 24/22 (1.091)
←
5th 20/21 (0.952)
←
Chassis:
Frame type Semi double cradle
Caster angle 27.8˚
Trail 123 mm (4.84 in)
Tire:
Type With tube
Size (front) 80/100-21 51M (For USA, CDN, ZA, AUS, NZ
and F)
80/100-21 51R (For EUROPE except F)
Size (rear) 110/90-19 62M (For USA, CDN, ZA, AUS, NZ
and F)
110/90-19 NHS (For EUROPE except F)
Tire pressure (front and rear) 100 kPa (1.0 kgf/cm
2

, 15 psi)

2

SPEC

2 - 7
MAINTENANCE SPECIFICATIONS
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)0.12 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)0.12 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

2 - 11
MAINTENANCE SPECIFICATIONS
Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Spark plug M10S
×
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 13 1.3 9.4
(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

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
Sub wire harness
7
TPS (throttle position
sensor) lead
8
Neutral switch lead
9
Oil hose
0
Hose holder
A
CDI magneto lead
B
Clutch cable
C
Cylinder head breather hose
D
Carburetor breather hose
E
Overflow hose
Å
Pass the clutch cable through
the cable guide.
ı
Pass the fuel tank breather hose
between the handlebar and ten-
sion bar, then insert its end into
the hole of the number plate.
Ç
Pass the decompression cable
under the oil tank breather pipe.
Î
Fasten the CDI magneto lead
and neutral switch lead to the
frame with a plastic locking tie
and cut off the tie end.
‰
Fasten the sub wire harness to
the frame at the white tape for
the sub wire harness with a
plastic locking tie and cut off the
tie end.
Ï
Pass the cylinder head breather
hose along the right side of the
oil tank breather hose.
Ì
Fasten the sub wire harness to
the frame with a plastic locking
tie ends at the lower left of the
frame and cut off the tie end. For
fastening, pass the plastic lock-
ing tie through the upper holes
in the engine brackets.
Ó
Pass the sub wire harness
between the engine brackets.

2 - 22
SPEC

CABLE ROUTING DIAGRAM
È
Fasten the TPS lead (in the
sub wire harness) under the
frame so that it does not con-
tact the carburetor.
Ô
Make sure that the TPS lead
coupler does not go outside the
chassis.

Fasten the TPS lead under the
coupler to the frame with a
plastic locking tie.
Ò
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.ˆFasten the cylinder head
breather hose with the hose
holder.
ØFasten the neutral switch lead
to the frame with a plastic band
ends toward the rear of the
frame.
∏Fasten the cylinder head
breather hose with the hose
holder.
ŒPass the clutch cable through
the cable guide.
ÂFasten the neutral switch lead
and CDI magneto lead together
with a plastic band.
ÍPass the clutch cable on the
inside the cylinder head
breather hose.ÊPass the cylinder head
breather hose along the inner
side of the radiator pipe.
ËPass 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.

2 - 24
SPECCABLE ROUTING DIAGRAM
1Clamp
2Ignition coil
3High tension cord
4CDI unit
5CDI unit band
6“ENGINE STOP” button
lead
7Throttle cable (pull)
8Throttle cable (return)
9Radiator (left)
0Radiator breather hose
ARadiator (right)
BCDI unit stay (frame)ÅFasten the ignition coil lead to the
frame with a plastic band.
ıFasten the ignition coil and ground
lead to the frame with the bolt.
ÇPass the ignition coil lead (in the
sub wire harness) so that it does
not contact the carburetor and
rear shock absorber and connect
it with the lead from the ignition
coil on the inside of the frame.
ÎPass the throttle cables over the
high tension cord.
‰Pass the throttle cables along the
outer side of the CDI unit leads.
ÏFasten the CDI unit leads and
“ENGINE STOP” button lead to the
frame at the protector of the CDI
unit leads with a plastic locking tie.
ÌPass the radiator breather hose
on the outside the CDI unit lead
and “ENGINE STOP” button lead.ÓPass the CDI unit lead and
“ENGINE STOP” button lead over
the top radiator mounting boss.
ÈPass the throttle cables and
“ENGINE STOP” button lead
through the cable guide.
ÔCross the pull and return throttle
cables before the radiator.
Pass the throttle cables, “ENGINE
STOP” button lead and CDI unit
lead through the cable guide.
ÒPass the throttle cables between
the top radiator mounting boss and
middle radiator mounting boss.
˜Pass the radiator breather hose
between the frame and the radia-
tor without pinching it.
ˆPass the radiator breather hose
behind the decompression cable.
ØInsert the CDI unit band over the
CDI unit stay (frame) as far as
possible.

3 - 1
INSP
ADJ

MAINTENANCE INTERVALS
EC300000
REGULAR INSPECTION AND ADJUSTMENTS
MAINTENANCE INTERVALS
The following schedule is intended as a general guide to maintenance and lubrication. Bear in mind
that such factors as weather, terrain, geographical location, and individual usage will alter the
required maintenance and lubrication intervals. If you are a doubt as to what intervals to follow in
maintaining and lubricating your machine, consult your Yamaha dealer.
ItemAfter
break-inEvery
race
Every
third
(or
500 km)Every
fifth
(or
1,000 km)
As re-
quiredRemarks
ENGINE OIL
Replace
●

●

OIL FILTER
Clean
●●

VALVES
Check the valve clearances.
Inspect
Replace
●

●

●

●
The engine must be cold.
Check the valve seats
and valve stems for wear.
VALVE SPRINGS
Inspect
Replace
●

●
Check the free length and
the tilt.
VALVE LIFTERS
Inspect
Replace
●

●
Check for scratches and
wear.
CAMSHAFTS
Inspect
Replace
●

●
Inspect the camshaft sur-
face.
CAMSHAFT SPROCKETS
Inspect
Replace
●

●
Check for wear on the
teeth and for damage.
PISTON
Inspect
Clean
Replace
●

●

●

●
Inspect crack
Remove carbon
PISTON RING
Inspect
Replace
●

●

●
Check ring end gap
PISTON PIN
Inspect
Replace
●

●

CYLINDER HEAD
Inspect and clean
●
Remove carbon
Change gasket
CYLINDER
Inspect and clean
Replace
●

●
Inspect score marks
Inspect wear
CLUTCH
Inspect and adjust
Replace
●

●

●
Inspect housing, friction
plate, clutch plate and
spring
TRANSMISSION
Inspect
Replace bearing
●

●

3 - 4
INSP
ADJ
PRE-OPERATION INSPECTION AND MAINTENANCE
EC320000
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation, practice or a race, make sure the machine is in good operating
condition.
Before using this machine, check the following points.
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
CoolantCheck that coolant is filled up to the radiator filler cap.
Check the cooling system for leakage.P.3-5 ~ 9
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the
fuel line for leakage.P.1-14
Engine oilCheck that the oil level is correct. Check the crankcase and
frame oil line for leakage.P.3-13 ~ 17
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-9
Throttle grip/HousingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-10 ~ 11
Brakes Check the play of front brake and effect of front and rear brake. P.3-24 ~ 30
ChainCheck chain slack and alignment. Check that the chain is lubri-
cated properly.P.3-31 ~ 33
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-41 ~ 42
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-42 ~ 43
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage. P.3-33 ~ 40
Cables (wires)Check that the clutch and throttle cables move smoothly. Check
that they are not caught when the handlebars are turned or
when the front forks travel up and down.—
Muffler Check that the muffler is tightly mounted and has no cracks.—
Sprocket Check that the driven sprocket tightening bolt is not loose. P.3-31
Lubrication Check for smooth operation. Lubricate if necessary. P.3-44
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-19
Lead connectorsCheck that the CDI magneto, CDI unit, and ignition coil are con-
nected tightly.P.1-6
SettingsIs the machine set suitably for the condition of the racing course
and weather or by taking into account the results of test runs
before racing? Are inspection and maintenance completely
done?P.7-1 ~ 21