2001 YAMAHA YZ426F oil pressure

SPEC

2 - 2
GENERAL SPECIFICATIONS
Oil capacity:
Engine oil
Periodic oil change 1.5 L (1.32 Imp qt, 1.59 US qt)
With oil filter replacement 1.6 L (1.41 Imp qt, 1.69 US qt)
Total amount 1.7 L (1.50 Imp qt, 1.80 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 fuel with a research octane
number of 95 or higher. (Except for AUS)
Unleaded fuel only (For AUS)
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 kg/cm
2

, 15 psi)

2

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 - 10
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 - 13
MAINTENANCE SPECIFICATIONS
EC212201
CHASSIS
Item Standard Limit
Steering system:
Steering bearing type Taper roller bearing ----
Front suspension: USA, CDN AUS,
NZ, ZAEUROPE
Front fork travel 300 mm (11.8 in)¬----
Fork spring free length 460 mm (18.1 in)¬455 mm (17.9 in)
Spring rate, STD K = 4.51 N/mm
(0.46 kg/mm,
25.8 lb/in)K = 4.41 N/mm
(0.45 kg/mm,
25.2 lb/in)----
Optional spring/spacer Yes¬----
Oil capacity 578 cm
3
(20.3 lmp oz,
19.5 US oz) ¬----
Oil level 130 mm (5.12 in)¬----

(From top of outer tube with inner
tube and damper rod fully com-
pressed without spring.)80 ~ 150 mm
(3.15 ~ 5.91 in)¬----
Oil grade Suspension oil
“01”¬----
Inner tube outer diameter 46 mm (1.81 in)¬----
Front fork top end 0 mm (0 in)¬----
Rear suspension: USA, CDN,
AUS, NZ, ZAEUROPE
Shock absorber travel 132 mm
(5.20 in)¬----
Spring free length 265 mm
(10.43 in)275 mm
(10.83 in)----
Fitting length 248 mm
(9.76 in)262 mm
(10.31 in)----
247 ~ 265 mm
(9.72 ~ 10.43 in)257 ~ 275 mm
(10.12 ~ 10.83 in)----
Spring rate, STD K = 53.0 N/mm
(5.40 kg/mm,
302.4 lb/in)K = Approx.
53.0 N/mm
(5.40 kg/mm,
302.4 lb/in)----
Optional spring Yes¬----
Enclosed gas pressure 1,000 kPa
(10 kg/cm
2,
142 psi)¬----
Swingarm:
Swingarm free play limit
End ---- 1.0 mm (0.04 in)

3 - 3
INSP
ADJ

MAINTENANCE INTERVALS
REAR SHOCK ABSORBER
Inspect and adjust
Lube
Retighten
c

c

c

c

c

c Molybdenum disulfide
grease
CHAIN GUARD AND ROLLERS
Inspect
c c
SWINGARM
Inspect and retighten
c c
RELAY ARM, CONNECTING ROD
Inspect and lube
c c Molybdenum disulfide
grease
STEERING HEAD
Inspect free play and retighten
Clean and lube
Replace bearing
c c
c
c Lithium base grease
TIRE, WHEELS
Inspect air pressure, wheel run-out,
tire wear and spoke looseness
Retighten sprocket bolt
Inspect bearings
Replace bearings
Lubricate
c
c
c
c
c
c
c
Lithium base grease
THROTTLE, CONTROL CABLE
Check routing and connection
Lubricate
c
c
c
c Yamaha cable lube or
SAE 10W-30 motor oil ItemAfter
break-inEvery
race
Every
third
(or
500 km)Every
fifth
(or
1,000 km)As re-
quiredRemarks

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.1-13 ~ 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.1-18
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

3 - 17
INSP
ADJ
PILOT SCREW ADJUSTMENT
12. Check:
lOil pressure
Checking steps:
lSlightly loosen the oil gallery bolt 1.
lStart the engine and keep it idling until oil
starts to seep from the oil gallery bolt. If no
oil comes out after one minute, turn the
engine off so it will not seize.
lCheck oil passages, oil filter and oil pump
for damage or leakage.
lStart the engine after solving the prob-
lem(s) and recheck the oil pressure.
lTighten the oil gallery bolt to specification.
T R..
Oil gallery bolt:
18 Nm (1.8 m • kg, 13 ft • lb)
PILOT SCREW ADJUSTMENT
1. Adjust:
lPilot screw 1
Adjusting steps:
NOTE:
To optimize the fuel flow at a smaller throttle
opening, each machine’s pilot screw has
been individually set at the factory. Before
adjusting the pilot screw, turn it in fully and
count the number of turns. Record this num-
ber as the factory-set number of turns out.
lTurn in the pilot screw until it is lightly
seated.
lTurn out the pilot screw by the factory-set
number of turns.
Pilot screw:
1-1/4 turns out (example)

4 - 45
ENG

CLUTCH
CLUTCH
CLUTCH
Extent of removal:
1
Push rod and push lever removal
2
Push pod 1 disassembly
3
Friction plate and clutch plate removal
4
Clutch housing removal
Extent of removal Order Part name Q’ty Remarks
CLUTCH REMOVAL
Preparation for removal Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Brake pedal Refer to “ENGINE REMOVAL” section.
Clutch cable Disconnect at engine side.
1 Clutch cover 1
2 Gasket 1
3 Dowel pin 2
4 Clutch spring 6
5 Pressure plate 1
6 Push rod 1 1
7 Circlip 1
8 Plain washer 1
9 Bearing 1
10 Ball 1
11Push rod 2
1
41
2
3
1