2004 YAMAHA TTR125 fuel

4 - 5
ENG

CARBURETOR
HANDLING NOTE
At high altitudes, the atmospheric pressure is
lower. This can make the fuel mixture too rich,
leading to such problems as fouled.
Spark plugs and slow response at high engine
speeds. A special part, High Altitude Main Jet
1
#102.5 (620-1423A-71-A0) is available to
correct this.
EC463000
REMOVAL POINTS
Throttle valve
1. Remove:

Throttle valve
1


Spring (throttle valve)
2


Carburetor top cover
3


Throttle cable
4

NOTE:

While compressing the spring (throttle valve),
disconnect the throttle cable.
Pilot air screw
1. Remove:

Pilot air screw
1

NOTE:

To optimize the fuel flow at a smaller throttle
opening, each machine’s pilot air screw has
been individually set at the factory. Before
removing the pilot air screw, turn it in fully and
count the number of turns. Record this number
as the factory-set number of turns out.

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
ENG
EC4L0000
CDI MAGNETO (TT-R125/TT-R125LW)
Extent of removal:1 CDI magneto removal
Extent of removal Order Part name Q’ty Remarks
CDI MAGNETO REMOVAL
Preparation for removal Seat and fuel tank Refer to “SAET, FUEL TANK AND SIDE
COVERS” section.
Drain the engine oil Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.
Drive sprocket cover Refer to “ENGINE REMOVAL” section.
1 CDI magneto lead 1
2 Left crankcase cover 1
3 Nut (rotor) 1
Use special tool.
Refer to “REMOVAL POINTS”.
4 Rotor 1
5 Woodruff key 1
6 Pickup coil 1
7 Lead guide 1
8Stator
1
1
CDI MAGNETO (TT-R125/TT-R125LW)

4 - 61
ENG
CDI MAGNETO AND STARTER CLUTCH
(TT-R125E/TT-R125LWE)
CDI MAGNETO AND STARTER CLUTCH (TT-R125E/TT-R125LWE)
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 - 66
ENGENGINE 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
for the TT-R125E/TT-R125LWE.
Starter motor for the TT-R125E/
TT-R125LWERefer to “ELECTRIC STARTING SYS-
TEM” section in the CHAPTER 6 for the
TT-R125E/TT-R125LWE.
Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.

5 - 65
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.
WARNINGSupport 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