crankcase YAMAHA TTR125 2003 Owners Manual

CHAPTER 4
ENGINE
SEAT, FUEL TANK
AND SIDE COVERS
..................................4-1
MUFFLER
..................................................4-2
CARBURETOR
..........................................4-3
CYLINDER HEAD
....................................4-12
CAMSHAFT AND ROCKER ARMS
........4-20
VALVES AND VALVE SPRINGS
............4-24
CYLINDER AND PISTON
........................4-32
CLUTCH AND PRIMARY
DRIVEN GEAR
........................................4-40
OIL PUMP
................................................4-49
KICK AXLE AND SHIFT SHAFT
.............4-53
CDI MAGNETO
AND STARTER CLUTCH
.........................4-58
ENGINE REMOVAL
.................................4-63
CRANKCASE, CRANKSHAFT
AND BALANCER
....................................4-67
TRANSMISSION, SHIFT CAM
AND SHIFT FORK
...................................4-75
CHAPTER 5
CHASSIS
FRONT WHEEL AND FRONT BRAKE
(TT-R125E)
................................................5-1
FRONT WHEEL (TT-R125LWE)
...............5-8
FRONT BRAKE (TT-R125LWE)
..............5-12
REAR WHEEL AND REAR BRAKE
.......5-24
FRONT FORK
..........................................5-32
HANDLEBAR
...........................................5-41
STEERING
...............................................5-48
SWINGARM
.............................................5-54
REAR SHOCK ABSORBER
ASSEMBLY
.............................................5-61
CHAPTER 6
ELECTRICAL
ELECTRICAL COMPONENTS
AND WIRING DIAGRAM
...........................6-1
IGNITION SYSTEM
....................................6-2
ELECTRIC STARTING SYSTEM
...............6-6
CHARGING SYSTEM
...............................6-16

1 - 6
GEN
INFO
SPECIAL TOOLS
SPECIAL TOOLS
The proper special tools are necessary for complete and accurate tune-up and assembly. Using the
correct special tool will help prevent damage caused by the use of improper tools or improvised
techniques. The shape and part number used for the special tool differ by country, so two types are
provided. Refer to the list provided to avoid errors when placing an order.
NOTE:
For U.S.A. and CDN, use part number starting with “YM-”, “YU-”, “YS-” or “ACC-”.
For others, use part number starting with “90890-”.
Part number Tool name/How to use Illustration
YU-1083-A
90890-01084
90890-01085Small slide hammer set
Weight
Slide hammer bolt
These tools are used when removing or installing the
rocker arm shafts.YU-1083-A 90890-01084
90890-01085
YU-1135-A, 90890-01135 Crankcase separating tool
These tools are used to split the crankcase as well as
remove the crankshaft from either case.YU-1135-A 90890-01135
YU-3097, 90890-01252
YU-1256Dial gauge & stand set
Stand
These tools are used to check each part for runout or
bend.YU-3097
YU-125690890-01252
YU-90050, 90890-01274
YU-90050, 90890-01275
YU-90063, 90890-01278
YU-91044, 90890-04081Crankcase installing tool
Crankshaft installer pot
Crankshaft installer bolt
Adaptor
Spacer (crankshaft installer)
These tools are used to install the crankshaft.YU-90050
YU-91044
YU-9006390890-01274
90890-01275
90890-01278
90890-04081
YM-1326, 90890-01326
YM-1300, 90890-01294T-handle
Damper rod holder
These tools are used for holding the damper rod
holder when removing or installing the damper rod
holder.YM-1326
YM-130090890-01326
90890-01294
YU-1304, 90890-01304 Piston pin puller set
This tool is used to remove the piston pin.YU-1304 90890-01304
YM-8035, 90890-01311 Tappet adjusting tool
This tool is necessary for adjusting valve clearance.YM-8035 90890-01311

1 - 8
GEN
INFO
SPECIAL TOOLS
YM-4097, 90890-04097
YM-4098, 90890-04098
YM-04099, 90890-04099Valve guide remover
Valve guide installer
Valve guide reamer
These tools are needed to rebore the new valve
guide.YM-4097
YM-4098
YM-0409990890-04097
90890-04098
90890-04099
YM-34487
90890-06754Dynamic spark tester
Ignition checker
This instrument is necessary for checking the ignition
system components.YM-34487 90890-06754
ACC-QUICK-GS-KT
90890-85505Quick gasket
®
YAMAHA Bond No.1215
This sealant (Bond) is used for crankcase mating
surface, etc.ACC-QUICK-GS-KT 90890-85505
Part number Tool name/How to use Illustration

SPEC

2 - 13
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
Cylinder head bolt M8
×
1.25 4 22 2.2 16
Cylinder head bolt M6
×
1.0 2 10 1.0 7.2
Oil pressure check bolt M6
×
1.0 1 7 0.7 5.1
Cylinder head side cover M6
×
1.0 2 10 1.0 7.2
Tappet cover M45
×
1.5 2 18 1.8 13
Timing chain guide M6
×
1.0 1 10 1.0 7.2
Adjusting screw (valve) and locknut M5
×
0.5 2 8 0.8 5.8
Camshaft sprocket M8
×
1.25 1 20 2.0 14
Bearing plate cover (camshaft) M6
×
1.0 1 10 1.0 7.2
Timing chain tensioner cap bolt M6
×
1.0 1 8 0.8 5.8
Timing chain tensioner M6
×
1.0 2 10 1.0 7.2
Oil pump assembly M6
×
1.0 2 7 0.7 5.1
Oil pump cover M5
×
0.8 1 5 0.5 3.6
Engine oil drain bolt M12
×
1.5 1 20 2.0 14
Carburetor joint M6
×
1.0 2 10 1.0 7.2
Carburetor joint clamp (air filter) M4
×
0.7 1 2 0.2 1.4
Coasting enricher cover M4
×
0.7 2 2 0.2 1.4
Air filter case M6
×
1.0 3 7 0.7 5.1
Muffler M6
×
1.0 2 10 1.0 7.2
Muffler M10
×
1.25 1 60 6.0 43
Muffler M8
×
1.25 1 30 3.0 22
Muffler guard M6
×
1.0 7 10 1.0 7.2
Spark arrester M6
×
1.0 3 10 1.0 7.2
Crankcase M6
×
1.0 10 10 1.0 7.2
Left crankcase cover M6
×
1.0 7 10 1.0 7.2
Drive sprocket cover M6
×
1.0 2 12 1.2 8.7
Right crankcase cover M6
×
1.0 9 10 1.0 7.2
Lead guide (CDI magneto lead) M6
×
1.0 1 7 0.7 5.1
Timing mark accessing screw M14
×
1.5 1 7 0.7 5.1
Crankshaft end accessing screw M32
×
1.5 1 7 0.7 5.1
Kickstarter crank M12
× 1.0 1 50 5.0 36
Starter clutch M8 × 1.25 3 30 3.0 22
Plate (starter idle gear) M6 × 1.0 2 7 0.7 5.1
Primary drive gear M12 × 1.0 1 70 7.0 50
Clutch spring M5 × 0.8 4 6 0.6 4.3
Clutch boss M12 × 1.0 1 60 6.0 43
Adjusting screw (push rod) and locknut M6 × 1.0 1 8 0.8 5.8
Bearing plate cover (main axle) M6 × 1.0 2 7 0.7 5.1
Drive sprocket M5 × 0.8 2 6 0.6 4.3
Shift arm M6 × 1.0 1 10 1.0 7.2
Shift rod and shift pedal M6 × 1.0 1 7 0.7 5.1
Shift rod and shift arm M6 × 1.0 1 7 0.7 5.1
Shift pedal M6 × 1.0 1 12 1.2 8.7

2 - 27
SPEC

CABLE ROUTING DIAGRAM
Î
After fastening the starter relay
lead, pass it on the left of the
chassis.
‰
Fasten the CDI magneto lead
and starter relay lead.
Ï
Fasten the wire harness.
Ì
Pass the rectifier/regulator lead
between the frame and air filter
case.
Ó
Do not allow the CDI magneto
lead to slacken except between
the two plastic locking ties.
È
Fasten the CDI magneto lead
over the engine bracket (rear).
Ô
Fasten the CDI magneto lead.

Pass the air vent hoses between
the engine and swingarm.
Ò
Fit the neutral switch lead into
the groove in the crankcase
cover.
˜
Pass the starting circuit cut-off
relay lead under the frame and
at the right of the chassis.
ˆ
Fasten the rear shock absorber
assembly sub-tank.
(TT-R125LWE only)
Ø
Pass the CDI unit lead on the
outside of the main switch lead,
engine stop switch lead, clutch
switch lead and start switch
lead.
∏After fastening the start switch
lead, clutch switch lead, engine
stop switch lead and main
switch lead, push their corru-
gated tube against the CDI unit
coupler.
ŒFasten the brake hose between
the paint marks.
ÂPass the brake hose (brake
cable for the TT-R125E)
through the cable guide.
ÍFit the CDI unit band over the
CDI unit bracket till it stops.
ÊFasten the brake cable.
30~35 mm
(1.18~1.38 in)
E
DD
A
C
B-B
D-D
E
B
BC
TT-R125EA
L
1
3
4 2
3
35
3
36
7
3
3
8
9 0 A 3 B C
DEFGHIJKOP
7
4
0
3 3M
N
3Q
3 F
E
DË
◊
„
Ù
AB
AA
Û
ÁAC
N
Ì
Ï ‰ Î
Ç ı Å
Ó
È
Ô

Ò ˜ ˆ Ø ∏
ŒÂÍ ÊÂ

3 - 3
INSP
ADJ

PRE-OPERATION INSPECTION AND MAINTENANCE
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation or practice, make sure the machine is in good operating condi-
tion.
Before using this machine, check the following points.
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the
fuel line for leakage.P.1-12
Engine oilCheck that the oil level is correct. Check the crankcase for leak-
age.P.3-7 ~ 10
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-4
Throttle grip/housingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-4 ~ 5
BrakesCheck the play of front and rear brake and effect of front and
rear brake.
Check fluid level and leakage. (TT-R125LWE only)P.3-15 ~ 20
Drive chainCheck chain slack and alignment. Check that the chain is lubri-
cated properly.P.3-21 ~ 22
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-27 ~ 28
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-28 ~ 30
Front forks and rear shock
absorber assemblyCheck that they operate smoothly and there is no oil leakage. P.3-23 ~ 26
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. P.4-2
Sprocket Check that the driven sprocket tightening nut is not loose. P.3-20
Lubrication Check for smooth operation. Lubricate if necessary. P.3-31
Bolts and nuts Check the chassis and engine for loose bolts and nuts. —
Lead connectorsCheck that the CDI magneto, CDI unit, and ignition coil are con-
nected tightly.P.1-5

3 - 8
INSP
ADJ
ENGINE OIL LEVEL INSPECTION
4. Check:
Oil level
Oil level should be between maximum
a and minimum b marks.
Oil level is low → Add oil to proper
level.
NOTE:
When inspecting the oil level, do not screw the
dipstick into the oil tank. Insert the gauge
lightly.
(For USA and CDN)
CAUTION:
Do not add any chemical additives.
Engine oil also lubricates the clutch and
additives could cause clutch slippage.
Do not allow foreign material to enter the
crankcase.
Recommended oil:
At –10 ˚C (10 ˚F) or higher Å:
Yamalube 4 (10W-30) or SAE
10W-30 type SE motor oil
At 5 ˚C (40 ˚F) or higher ı:
Yamalube 4 (20W-40) or SAE
20W-40 type SE motor oil
(Except for USA and CDN)
CAUTION:
Do not add any chemical additives or use
oils with a grade of CD a or higher.
Do not use oils labeled “ENERGY CON-
SERVING II” b or higher. Engine oil also
lubricates the clutch and additives could
cause clutch slippage.
Do not allow foreign materials to enter the
crankcase.
Recommended oil:
Refer to the following chart for
selection of oils which are suited
to the atmospheric temperatures.
Recommended engine oil classi-
fication:
API STANDARD:
API “SE” or higher grade
(Designed primarily for motor-
cycles)

3 - 12
INSP
ADJ
VALVE CLEARANCE INSPECTION AND ADJUSTMENT
4. Check:
Valve clearance
Out of specification → Adjust.
Valve clearance (cold):
Intake valve:
0.08 ~ 0.12 mm
(0.0031 ~ 0.0047 in)
Exhaust valve:
0.10 ~ 0.14 mm
(0.0039 ~ 0.0055 in)
Checking steps:
Turn the crankshaft counterclockwise with
a wrench.
Align the T.D.C. mark a on the rotor with
the align mark b on the crankcase cover
when piston is at T.D.C. on compression
stroke.
Measure the valve clearance using a
feeler gauge 1.
Out of specification → Adjust clearance.
5. Adjust:
Valve clearance
Adjustment steps:
Loosen the locknut 1.
Turn the adjuster 3 in or out with the
valve adjusting tool 2 until specified clear-
ance is obtained.
Turning in →
Valve clearance is decreased.
Turning out →
Valve clearance is increased.
Tappet adjusting tool:
YM-8035/90890-01311
Hold the adjuster to prevent it from moving
and tighten the locknut.
T R..
Locknut:
8 Nm (0.8 m • kg, 5.8 ft • lb)

4 - 14
ENGCYLINDER HEAD
REMOVAL POINTS
Cylinder head
1. Align:
“I” mark
(with stationary pointer)
Checking steps:
Turn the crankshaft counterclockwise with
a wrench.
Align the “I” mark a on the rotor with the
stationary pointer b on the crankcase
cover. When the “I” mark is aligned with
the stationary pointer, the piston is at the
Top Dead Center (T.D.C.).
NOTE:
In order to be sure that the piston is at Top
Dead Center, the match mark c on the
camshaft sprocket must align with the sta-
tionary pointer d on the cylinder head as
shown in the illustration.
2. Loosen:
Camshaft sprocket bolt 1
NOTE:
Remove the bolt while holding the rotor nut
with a wrench.
3. Remove:
Bolt (timing chain tensioner cap) 1
Bolt (timing chain tensioner) 2
Timing chain tensioner 3

4 - 15
ENGCYLINDER HEAD
4. Remove:
Bolt (camshaft sprocket) 1
Camshaft sprocket 2
NOTE:
Attach a wire a to the timing chain to prevent
it from falling into the crankcase.
5. Remove:
Bolts (cylinder head)
Cylinder head
NOTE:
Loosen the bolts 1/4 turn each and remove
then after all are loosened.
Loosen the bolts starting with the lowest
number one.
INSPECTION
Cylinder head
1. Eliminate:
Carbon deposits (from the combustion
chambers)
Use a rounded scraper.
NOTE:
Do not use a sharp instrument to avoid dam-
aging or scratching:
Spark plug threads
Valve seats
2. Inspect:
Cylinder head
Scratches/damage → Replace.
3. Inspect:
Cylinder head warpage
Out of specification → Re-surface.
Warpage measurement and re-surfacing
steps:
Attach a straightedge and a thickness
gauge on the cylinder head.
Measure the warpage.