2000 YAMAHA YZ426F water pump

4 - 51
ENG
OIL FILTER, WATER PUMP AND CRANKCASE COVER
(RIGHT)
EC4G5220
Impeller shaft
1. Install:
lImpeller shaft 1
lPlain washer 2
lImpeller shaft 3
NOTE:
lTake care so that the oil seal lip is not dam-
aged or the spring does not slip off its posi-
tion.
lWhen installing the impeller shaft, apply the
engine oil on the oil seal lip and impeller
shaft. And install the shaft while turning it.
lHold the impeller shaft on its width across
the flats a with spanners, etc. and remove
the impeller.
Crankcase cover (right)
1. Install:
lDowel pin 1
lO-ring 2
lCollar 3
lGasket 4 New
2. Install:
lCrankcase cover (right) 1
lBolt
NOTE:
lWhen installing the crankcase cover onto the
crankcase, be sure that the impeller shaft
end 2 aligns with the balancer end slot 3.
lTighten the bolts in stage, using a crisscross
pattern.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

4 - 52
ENG
OIL FILTER, WATER PUMP AND CRANKCASE COVER
(RIGHT)
Kick crank
1. Install:
lKick crank 1
NOTE:
Install the kick crank so that the kick crank is
as vertical as possible with the distance a
between the kick crank and the frame being
5 mm (0.20 in) or more.
T R..33 Nm (3.3 m · kg, 24 ft · lb)
2. Install:
lOil hose 1
lBolt (oil hose) 2
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
3. Install:
lCopper washer 1
lOil delivery pipe 2
lUnion bolt (M8) 3
lUnion bolt (M10) 4
T R..18 Nm (1.8 m · kg, 13 ft · lb)
T R..20 Nm (2.0 m · kg, 14 ft · lb)
Water pump housing
1. Install:
lPin 1
lO-ring 2 New
2. Install:
lWater pump housing 1
lBolt (water pump housing) 2
lPlain washer 3
lCoolant drain bolt 4
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
New
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

ENG
4 - 53
BALANCER
BALANCER
BALANCER
Extent of removal:1 Balancer drive gear2 Balancer
Extent of removal Order Part name Q’ty Remarks
BALANCER REMOVAL
Preparation for removal Clutch housing Refer to “CLUTCH” section.
Crankcase cover (right)Refer to “OIL FILTER, WATER PUMP AND
CRANKCASE COVER (RIGHT)” section.
Stator Refer to “CDI MAGNETO” section.
1 Nut (primary drive gear) 1
Refer to “REMOVAL POINTS”. 2 Nut (balancer) 1
3 Lock washer 1
4 Primary drive gear 1
5 Balancer drive gear 1
6 Straight key 1
7 Lock washer 1
8 Balancer driven gear 1
9Balancer
1
2
1
2

ENG
4 - 56
OIL PUMP
OIL PUMP
OIL PUMP
Extent of removal:1 Oil pump removal2 Oil pump disassembly
Extent of removal Order Part name Q’ty Remarks
OIL PUMP REMOVAL AND DIS-
ASSEMBLY
Preparation for removal Clutch housingRefer to “CLUTCH” section.
Crankcase cover (right)Refer to “OIL FILTER, WATER PUMP AND
CRANKCASE COVER (RIGHT)” section.
1 Circlip 1
2 Plate washer 1
3 Oil pump drive gear 1
4 Oil pump assembly 1
5 Dowel pin 1
6 Outer rotor 2 1
7 Circlip 1
8 Inner rotor 2 1
9 Pin 1
10 Oil pump cover 1
11 Outer rotor 1 1
12Inner rotor 1
1
2
1

7 - 1
TUN

EC700000
TUNING
EC710000
ENGINE
Carburetor setting
l
The air/fuel mixture will vary depending on
atmospheric conditions. Therefore, it is nec-
essary to take into consideration the air pres-
sure, ambient temperature, humidity, etc.,
when adjusting the carburetor.
l
Perform a test run to check for proper engine
performance (e.g., throttle response) and
spark plug(-s) discoloration or fouling. Use
these readings to determine the best possi-
ble carburetor setting.
NOTE:

It is recommended to keep a record of all car-
buretor settings and external conditions (e.g.,
atmospheric conditions, track/surface condi-
tions, lap times) to make future carburetor set-
ting easier.
WARNING

l
The carburetor is a part of the fuel line.
Therefore, be sure to install it in a well-
ventilated area, away from flammable
objects and any sources of fire.
l
Never look into the carburetor intake.
Flames may shoot out from the pipe if the
engine backfires while it is being started.
Gasoline may be discharged from the
accelerator pump nozzle when the carbu-
retor has been removed.
CAUTION:

l
The carburetor is extremely sensitive to
foreign matter (dirt, sand, water, etc.).
During installation, do not allow foreign
matter to get into the carburetor.
l
Always handle the carburetor and its com-
ponents carefully. Even slight scratches,
bends or damage to carburetor parts may
prevent the carburetor from functioning
correctly. Carefully perform all servicing
with the appropriate tools and without
applying excessive force.
l
When the engine is stopped or when
riding at no load, do not open and close
the throttle unnecessarily. Otherwise, too
much fuel may be discharged, starting
may become difficult or the engine may
not run well.
SETTING
7