Water YAMAHA YZ125LC 2004 User Guide

3-23
REAR BRAKE PAD INSULATOR INSPECTION
BRAKE FLUID LEVEL INSPECTIONINSP
ADJ
EC36b000
REAR BRAKE PAD INSULATOR
INSPECTION
1. Remove:
9Brake pad
Refer to
“REAR BRAKE PAD INSPEC-
TION AND REPLACEMENT” section.
2. Inspect:
9Rear brake pad insulator 1
Damage Replace.
EC367001
BRAKE FLUID LEVEL INSPECTION
1. Place the master cylinder so that its top is in
a horizontal position.
2. Inspect:
9Brake fluid level
Fluid at lower level Fill up.
aLower level
ÅFront
ıRear
w
9Use only designated quality brake fluid to
avoid poor brake performance.
9Refill with same type and brand of brake flu-
id; mixing fluids could result in poor brake
performance.
9Be sure that water or other contaminants do
not enter master cylinder when refilling.
9Clean up spilled fluid immediately to avoid
erosion of painted surfaces or plastic parts.
Recommended brake fluid:
DOT #4
5XE-9-30-3B 4/16/03 10:24 AM Page 10

4-20
ENGCYLINDER HEAD, CYLINDER AND PISTON
EC474000
INSPECTION
EC474102
Cylinder head
1. Eliminate:
9Carbon deposits
Use a rounded scraper 1.
NOTE:
Take care to avoid damaging the spark plug
threads. Do not use a sharp instrument. Avoid
scratching the aluminum.
2. Inspect:
9Cylinder head water jacket
Crust of minerals/Rust Remove.
9Cylinder head warpage
Out of specification Re-surface.
Warpage measurement and re-surface-
ment steps:
9Attach a straightedge 1and a thickness
gauge 2on the cylinder head.
9Measure the warpage.
9If the warpage is out of specification, resur-
face the cylinder head.
9Place # 400~600 grit wet sandpaper 3on
the surface plate, and re-surface the head
4using a figure-eight sanding pattern.
NOTE:
Rotate the cylinder head several times to
avoid removing too much material from one
side.
EC474201
Cylinder
1. Eliminate:
9Carbon deposits
Use a rounded scraper 1.
NOTE:
Do not use a sharp instrument. Avoid scratching
the aluminum.
Warpage limit:
0.03 mm(0.0012 in)
5XE-9-30-4B 3/24/03 11:18 PM Page 6

4-38
ENG
KICK AXLE, SHIFT SHAFT AND PRIMARY DRIVE
GEAR
Extent of removal Order Part name Q’ty Remarks
RPIMARY DRIVE GEAR REMOVAL
Preparation for Drain the transmission oil.Refer to “TRANSMISSION OIL REPLACE-
removalMENT“ section in the CHAPTER 3.
Clutch cable Disconnect at engine side.
Bolt (brake pedal) Shift the brake pedal downward.
Radiator hose 4 Disconnect at water pump side.
Bolt (push rod)
Refer to “CYLINDER HEAD, CYLINDER
AND PISTON” section.
1 Kick starter 1
2 Crankcase cover (right) 1
3 Bolt (Primary drive gear) 1 Only loosening
Refer to “REMOVAL POINTS”.
4 Primary driven gear 1 Refer to “CLUTCH AND PRIMARY
DRIVEN GEAR”section.
5 Primary drive gear 1
EC4C0000
KICK AXLE, SHIFT SHAFT AND PRIMARY DRIVE GEAREC4C8000PRIMARY DRIVE GEAR
1
Extent of removal:1Primary drive gear removal
10 Nm (1.0 m•kg, 7.2 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
55 Nm (5.5 m•kg, 40 ft•lb)
5XE-9-30-4C 4/16/03 10:31 AM Page 2

4-49
ENGWATER PUMP
Extent of removal Order Part name Q’ty Remarks
WATER PUMP DISASSEMBLY
Preparation for Crankcase cover (right)
Refer to “KICK AXLE, SHIFT SHAFT AND
removalPRIMARY DRIVE GEAR” section.
1 Water pump housing cover 1
2 Impeller 1
3 Plain washer 1 Refer to “REMOVAL POINTS”.
4 Impeller shaft 1
5 Bearing 1
6 Oil seal 2Refer to “REMOVAL POINTS”.
EC4G0000
WATER PUMP
1
2
Extent of removal:1Impeller shaft removal2Oil seal removal








14 Nm (1.4 m•kg, 10 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
5XE-9-30-4C 4/16/03 10:32 AM Page 24

4-50
ENGWATER PUMP
EC4G3000
REMOVAL POINTS
EC4G3110
Impeller shaft
1. Remove:
9Impeller 1
9Plain washer 2
9Impeller shaft 3
NOTE:
Hold the impeller shaft on its width across the
flats awith spanners, etc. and remove the im-
peller.
EC4G3210
Oil seal
NOTE:
It is not necessary to disassemble the water
pump, unless there is an abnormality such as
excessive change in coolant level, discoloration
of coolant, or milky transmission oil.
1. Remove:
9Bearing 1
2. Remove:
9Oil seal 1
EC4G4000
INSPECTIONEC444200
Impeller shaft
1. Inspect:
9Impeller shaft 1
Bend/Wear/Damage Replace.
Fur deposits Clean.
5XE-9-30-4C 4/16/03 10:32 AM Page 26

4-51
ENGWATER PUMP
EC444300
Impeller shaft gear
1. Inspect:
9Gear teeth a
Wear/Damage Replace.
EC4H4600
Bearing
1. Inspect:
9Bearing 1
Rotate inner race with a finger.
Rough spot/Seizure Replace.
EC444400
Oil seal
1. Inspect:
9Oil seal 1
Wear/Damage Replace.
EC4G5000
ASSEMBLY AND INSTALLATION
EC4G5111
Oil seal
1. Install:
9Oil seal 1
NOTE:
9Apply the lithium soap base grease on the oil
seal lip.
9Install the oil seal with its manufacture's marks
or numbers facing the crankcase cover (right)
2.
2. Install:
9Bearing 1
NOTE:
Install the bearing by pressing its outer race par-
allel.
5XE-9-30-4C 4/16/03 10:32 AM Page 28

4-52
ENGWATER PUMP
EC4G5220
Impeller shaft
1. Install:
9Impeller shaft 1
NOTE:
9Take care so that the oil seal lip is not dam-
aged or the spring does not slip off its position.
9When installing the impeller shaft, apply the
lithium soap base grease on the oil seal lip and
impeller shaft. And install the shaft while turn-
ing it.
2. Install:
9Plain washer 1
9Impeller 2
NOTE:
Hold the impeller shaft on its width across the
flats awith spanners, etc. and install the im-
peller.
3. Install:
9Dowel pin 1
9Gasket (water pump housing cover) 2
4. Install:
9Water pump housing cover 1
9Bolt (water pump housing cover) 2
9Copper washer (coolant drain bolt) 3
9Coolant drain bolt 4
10 Nm (1.0 m•kg, 7.2 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
14 Nm (1.4 m•kg, 10 ft•lb)
5XE-9-30-4C 4/16/03 10:32 AM Page 30

4-57
ENGENGINE REMOVAL
Extent of removal Order Part name Q’ty Remarks
ENGINE REMOVAL
Preparation for
Hold the machine by placing the
removalsuitable stand under the engine.
Seat and fuel tankRefer to “SEAT, FUEL TANK AND
SIDE COVERS” section.
Carburetor Refer to “CARBURETOR AND REED
VALVE” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
Clutch cable Disconnect at engine side.
Radiator hose 2 Disconnect at cylinder head side.
Radiator hose 4 Disconnect at water pump side.
Bolt (radiator) Refer to “RADIATOR” section.
Radiator hose 3 Disconnect at right side radiator,
then shift the radiators forward.
Spark plug cap
Disconnect the CDI magneto lead.
EC4M0000
ENGINE REMOVAL
w
Support the machine securely so there is no dan-
ger of it falling over.
26 Nm (2.6 m•kg, 19 ft•lb)
34 Nm (3.4 m•kg, 24 ft•lb)
64 Nm (6.4 m•kg, 46 ft•lb)
64 Nm (6.4 m•kg, 46 ft•lb)
85 Nm (8.5 m•kg, 61 ft•lb)
65 Nm (6.5 m•kg, 47 ft•lb)
5 Nm (0.5 m•kg, 3.6 ft•lb)
5XE-9-30-4D 3/24/03 11:14 PM Page 2

5-24
CHASFRONT BRAKE AND REAR BRAKE
2. Install:
9Brake hose holder 1
9Screw (brake hose holder) 2
cC
After installing the brake hose holders,
make sure the brake hose does not contact
the spring (rear shock absorber). If it does,
correct its twist.
EC5A5620
Brake fluid
1. Fill:
9Brake fluid
Until the fluid level reaches “LOWER” level
line a.
w
9Use only the designated quality brake fluid:
otherwise, the rubber seals may deterio-
rate, causing leakage and poor brake per-
formance.
9Refill with the same type of brake fluid;
mixing fluids may result in a harmful chemi-
cal reaction and lead to poor performance.
9Be careful that water does not enter the
master cylinder when refilling. Water will
significantly lower the boiling point of the
fluid and may result in vapor lock.
cC
Brake fluid may erode painted surfaces or
plastic parts. Always clean up spilled fluid
immediately.
AFront
BRear
Recommended brake fluid:
DOT #4
1 Nm (0.1 m•kg, 0.7 ft•lb)
5XE-9-30-5A 4/28/03 6:07 PM Page 48

7-2
TUNSETTING
That is:
9Higher temperature expands the air with its
resultant reduced density.
9Higher humidity reduces the amount of oxygen
in the air by so much of the water vapor in the
same air.
9Lower atmospheric pressure (at a high altitude)
reduces the density of the air.
EC713001
Test run
After warming up the engine equipped with the
standard type carburetor(s) and spark plug(s),
run two or three laps of the circuit and check the
smooth operation of the engine and discoloration
of spark plug(s).
åNormal
∫Over burned (too lean)
çOil fouled (too rich)
Discoloration Condition of spark plug
NormalInsulator is dry and
burnt brown.
Over burned
Insulator is whitish.
(too lean)
Oil fouled Insulator is sooty and
(too rich) wet.
A
B
C
5XE-9-30-7A 4/30/03 9:39 AM Page 4