fuel YAMAHA TTR125 2003 Owner's Guide

4 - 7
ENGCARBURETOR
EC464301
Throttle valve
1. Check:
Free movement
Stick → Repair or replace.
NOTE:
Insert the throttle valve 1 into the carburetor
body, and check for free movement.
EC464401
Jet needle
1. Inspect:
Jet needle 1
Bends/wear → Replace.
Clip groove
Free play exists/wear → Replace.
Clip position
Fuel level
1. Measure:
Fuel level a
Out of specification → Adjust.
Standard clip position:
No. 2 Groove
Fuel level:
6.0 ~ 7.0 mm (0.24 ~ 0.28 in)
Below the float chamber mat-
ing surface
Measurement and adjustment steps:
Connect the fuel level gauge 1 to the float
chamber.
Fuel level gauge:
YM-1312-A/90890-01312
Hold the fuel level gauge vertically next to
the float chamber mating surface.
Loosen the drain screw.
Measure the fuel level with the fuel level
gauge.
NOTE:
Keep the carburetor and fuel level gauge
vertically when measuring the fuel level.
If the fuel level is not within specification,
inspect the needle valve seat and needle valve.
If either is worn, replace them both.
If both are fine, adjust the fuel level by
bending the float tab b on the float.
Recheck the fuel level.

4 - 11
ENGCARBURETOR
3. Install:
Carburetor top cover 1
Starter plunger 2
Air vent hose 3
Over flow hose 4
Fuel hose 5
NOTE:
Align the slit a of the throttle valve with the tab
b of the carburetor body.
CAUTION:
In order to release the starter cable from
the twist, install the starter knob after tight-
ening the nut for the starter plunger.
4. Adjust:
Idle speed
Refer to “ENGINE IDLING SPEED
ADJUSTMENT” section in the CHAP-
TER 3.

4 - 12
ENGCYLINDER HEAD
CYLINDER HEAD
CYLINDER HEAD SIDE COVER AND TAPPET COVER
Extent of removal:1 Cylinder head side cover and tappet cover removal
Extent of removal Order Part name Q’ty Remarks
CYLINDER HEAD SIDE COVER
AND TAPPET COVER
REMOVAL
Preparation for removal Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Muffler Refer to “MUFFLER” section.
Carburetor Refer to “CARBURETOR” section.
CDI unit Remove from the frame.
1 Engine bracket 1
2 Spark plug 1
3 Cylinder head side cover 1
4 Tappet cover 2
5 Crankshaft end accessing screw 1
6Timing mark accessing screw
1
1

4 - 58
ENGCDI MAGNETO AND STARTER CLUTCH
CDI MAGNETO AND STARTER CLUTCH
Extent of removal:1 Pickup coil/stator removal2 Starter clutch/wheel gear removal
Extent of removal Order Part name Q’ty Remarks
CDI MAGNETO AND STATOR
REMOVAL
Preparation for removal Fuel tank
1 CDI magneto lead 1
2 Neutral switch lead 1
3 Left crankcase cover 1
4 Nut (rotor) 1
Use special tool.
Refer to “REMOVAL POINTS”.
5 Rotor 1
6 Starter clutch 1
7 Woodruff key 1
8 Starter wheel gear 1
9 Plain washer 1
10 Plate (starter idle gear) 1
11 Starter idle gear 1
12 Lead guide 1
13Pickup coil/stator assembly
1
1
2
1
1

4 - 63
ENG

ENGINE REMOVAL
ENGINE REMOVAL
Extent of removal:
1
Engine removal
Extent of removal Order Part name Q’ty Remarks
ENGINE REMOVAL
Preparation for removal Hold the machine by placing the
suitable stand under the frame.
Seat, fuel tank and side covers Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Carburetor Refer to “CARBURETOR” section.
Muffler Refer to “MUFFLER” section.
Clutch cable Disconnect at engine side.
Spark plug cap
Disconnect the CDI magneto
lead.
Disconnect the neutral switch
lead.
Starter motor Refer to “ELECTRIC STARTING SYS-
TEM” section in the CHAPTER 6.
Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.

5 - 61
CHASREAR SHOCK ABSORBER ASSEMBLY
EC580000
REAR SHOCK ABSORBER ASSEMBLY
Extent of removal:1 Rear shock absorber assembly removal
Extent of removal Order Part name Q’ty Remarks
Preparation for removalREAR SHOCK ABSORBER
ASSEMBLY REMOVAL
Hold the machine by placing the
suitable stand under the engine.
WARNING
Support the machine securely so there is nodanger of it falling over.
Seat and side covers Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section in the CHAPTER 4.
1 Bolt (rear shock absorber assem-
bly-relay arm)1 Hold the swingarm.
2 Bolt (rear shock absorber assem-
bly-frame)1
3 Bushing 1 Refer to “REMOVAL POINTS”.
4 Rear shock absorber assembly 1
1

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6 - 2
IGNITION SYSTEM
EC620000
IGNITION SYSTEM
INSPECTION STEPS
Use the following steps for checking the possibility of the malfunctioning engine being attributable to
ignition system failure and for checking the spark plug which will not spark.
*marked: Only when the ignition checker is used.
NOTE:


Remove the following parts before inspection.
1) Seat
2) Fuel tank

Use the following special tools in this inspection.
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754
Pocket tester:
YU-3112-C/90890-03112
Spark gap test*Clean or replace
spark plug.
Check entire ignition
system for connection.Repair or replace.
Check main switch. Replace.
Check engine stop switch. Replace.
Check ignition coil. Primary coil Replace.
Secondary coil Replace.
Check CDI magneto. Pickup coil Replace.
Source coil Replace.
Replace CDI unit.
No Spark
OK
OK
OK
OK
Spark
No good
No good
No good
No good
No good
No good
OK
No good

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6 - 7
INSPECTION STEPS
If the starter motor will not operate, use the following inspection steps.
*1 marked: Refer to “FUSE INSPECTION” section in the CHAPTER 3.
*2 marked: Refer to “BATTERY INSPECTION AND CHARGING” section in the CHAPTER 3.
*3 marked: Refer to “MAIN SWITCH INSPECTION” section.
NOTE:
Remove the following parts before inspection.
1) Seat
2) Rear fender
3) Fuel tank
Use 12 V battery in this inspection.
Use the following special tools in this inspection.
Pocket tester:
YU-3112-C/90890-03112
*1 Check fuseReplace fuse and
check wire harness.
*2 Check battery Recharge or replace.
Check each coupler and
wire connection.Repair or replace.
*3 Check main switch. Replace.
Check starter motor
operation.Repair or replace.
Check starting circuit
cut-off relay.Replace.
Check starter relay. Replace.
Check neutral switch. Replace.
Check clutch switch. Replace.
Check start switch. Replace.
OK
OK
OK
OK
OK
OK
OK
OK
OK
No good
No good
No good
No good
No good
No good
No good
No good
No good
No good
ELECTRIC STARTING SYSTEM

–+ELEC
6 - 16
CHARGING SYSTEM
EC680000
CHARGING SYSTEM
EC681001
INSPECTION STEPS
If the battery is not charged, use the following inspection steps.
*1 marked: Refer to “FUSE INSPECTION” section in the CHAPTER 3.
*2 marked: Refer to “BATTERY INSPECTION AND CHARGING” section in the CHAPTER 3.
NOTE:
Remove the following parts before inspection.
1) Seat
2) Rear fender
3) Fuel tank
Use the following special tool in this inspection.
Pocket tester:
YU-3112-C/90890-03112Inductive tachometer:
YU-8036-B
Engine tachometer:
90890-03113
*1 Check fuse.Replace fuse and
check wire harness.
*2 Check battery. Recharge or replace.
Check each coupler and
wire connection.Repair or replace.
Check charging voltage.Charging system is
good.
Check CDI magneto. Charging coil Replace.
Replace rectifier/regulator.
OK
OK
OK
No good
OK
No good
No good
No good
No good
OK