2001 YAMAHA TTR125 engine spec

3 - 23
INSP
ADJFRONT FORK INSPECTION/
REAR SHOCK ABSORBER ASSEMBLY INSPECTION/
REAR SHOCK ABSORBER SPRING PRELOAD ADJUSTMENT
EC36C000
FRONT FORK INSPECTION
1. Inspect:
lFront fork smooth action
Operate the front brake and stroke the
front fork.
Unsmooth action/oil leakage ® Repair
or replace.
REAR SHOCK ABSORBER ASSEMBLY
INSPECTION
1. Inspect:
lSwingarm smooth action
Abnormal noise/unsmooth action ®
Grease the pivoting points or repair the
pivoting points.
Damage/oil leakage ® Replace.
REAR SHOCK ABSORBER SPRING
PRELOAD ADJUSTMENT
1. Elevate the rear wheel by placing the
suitable stand under the engine.
2. Remove:
lLeft side cover
3. Loosen:
lLocknut 1
4. Adjust:
lSpring preload
By turning the adjuster 2.
Stiffer ®Increase the spring preload.
(Turn the adjuster 2 in.)
Softer ®Decrease the spring preload.
(Turn the adjuster 2 out.)
Spring length (installed) a:
Standard length Extent of adjustment
165 mm
(6.50 in)155 ~ 175 mm
(6.10 ~ 6.89 in)

3 - 25
INSP
ADJSPOKES INSPECTION AND TIGHTENING/WHEEL INSPECTION/
STEERING HEAD INSPECTION AND ADJUSTMENT
SPOKES INSPECTION AND TIGHTENING
1. Inspect:
lSpokes 1
Bend/damage ® Replace.
Loose spoke ® Retighten.
2. Tighten:
lSpokes
NOTE:
Be sure to retighten these spokes before and
after break-in. After a practice check spokes
for looseness.
T R..Front 2 Nm (0.2 m · kg, 1.4 ft · lb)
Rear 3 Nm (0.3 m · kg, 2.2 ft · lb)
EC36T000
WHEEL INSPECTION
1. Inspect:
lWheel runout
Elevate the wheel and turn it.
Abnormal runout ® Replace.
2. Inspect:
lBearing free play
Exist play ® Replace.
STEERING HEAD INSPECTION AND
ADJUSTMENT
1. Elevate the front wheel by placing a suit-
able stand under the engine.
2. Check:
lSteering shaft
Grasp the bottom of the forks and gen-
tly rock the fork assembly back and
forth.
Free play ® Adjust steering head.

3 - 29
INSP
ADJ
ELECTRICAL/SPARK PLUG INSPECTION
EC370000
ELECTRICAL
EC371001
SPARK PLUG INSPECTION
1. Remove:
lSpark plug
2. Inspect:
lElectrode 1
Wear/damage ® Replace.
lInsulator color 2
Normal condition is a medium to light
tan color.
Distinctly different color ® Check the
engine condition.
NOTE:
When the engine runs for many hours at low
speeds, the spark plug insulator will become
sooty, even if the engine and carburetor are in
good operating condition.
3. Measure:
lPlug gap a
Use a wire gauge or thickness gauge.
Out of specification ® Regap.
4. Clean the plug with a spark plug cleaner
if necessary.
Spark plug gap:
0.6 ~ 0.7 mm (0.02 ~ 0.03 in)
Standard spark plug:
CR7HSA (NGK)
U22FSR-U (DENSO)
5. Tighten:
lSpark plug
NOTE:
lBefore installing a spark plug, clean the gas-
ket surface and plug surface.
lFinger-tighten a the spark plug before
torquing to specification b.
T R..13 Nm (1.3 m · kg, 9.4 ft · lb)

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:
l
Throttle valve
1

l
Spring (throttle valve)
2

l
Carburetor top cover
3

l
Throttle cable
4

NOTE:

While compressing the spring (throttle valve),
disconnect the throttle cable.
Pilot air screw
1. Remove:
l
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 - 16
ENG

CYLINDER HEAD
Warpage limit:
0.03 mm (0.0012 in)
l
If the warpage is out of specification,
resurface the cylinder head.
l
Place #400 ~ 600 grit wet sandpaper on
the surface plate, and re-surface the head
using a figure-eight sanding pattern.
NOTE:

Rotate the cylinder head several times to
avoid removing too much material from one
side.
ASSEMBLY AND INSTALLATION
Cylinder head
1. Install:
l
Dowel pin
1
lGasket 2 New
2. Install:
lCylinder head
lCopper washer
lBolt (cylinder head)
NOTE:
lApply Quick gasket® (YAMAHA Bond
No.1215) on end of the cylinder head bolts
(M6), as shown.
lApply the engine oil on the contact surfaces of
the bolts (cylinder head) and copper washers.
lFollow the numerical order shown in the illus-
tration. Tighten the bolts in two stages.
Quick gasket®:
ACC-QUICK-GS-KT
YAMAHA Bond No.1215:
90890-85505
T R..M8 22 Nm (2.2 m · kg, 16 ft · lb)
M6 10 Nm (1.0 m · kg, 7.2 ft · lb)

4 - 19
ENGCYLINDER HEAD
9. Check:
lValve clearance
Out of specification ® Adjust.
Refer to “VALVE CLEARANCE
INSPECTION AND ADJUSTMENT”
section in the CHAPTER 3.
10. Apply:
lEngine oil
On camshaft.
11. Install:
lTappet cover 1
lCylinder head side cover 2
T R..18 Nm (1.8 m · kg, 13 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
12. Install:
lTiming mark accessing screw 1
lCrankshaft end accessing screw 2
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
13. Install:
lSpark plug
lEngine bracket
T R..13 Nm (1.3 m · kg, 9.4 ft · lb)
T R..40 Nm (4.0 m · kg, 29 ft · lb)

4 - 22
ENG

CAMSHAFT AND ROCKER ARMS
Rocker arms and rocker arm shafts
1. Inspect:
l
Cam lobe contact surface
a

l
Adjuster surface
1

Wear/pitting/scratches/blue discolora-
tion
®
Replace.
Measurement steps:
l
Measure the inside diameter
a
of the
rocker arm holes.
Out of specification
®
Replace.
Inside diameter (rocker arm):
10.000 ~ 10.015 mm
(0.3937 ~ 0.3943 in)
: 10.03 mm (0.3949 in)
l
Measure the outside diameter
b
of the
rocker arm shafts.
Out of specification
®
Replace.
Outside diameter
(rocker arm shaft):
9.981 ~ 9.991 mm
(0.3930 ~ 0.3933 in)
: 9.95 mm (0.3917 in)
ASSEMBLY AND INSTALLATION
1. Apply:
l
Molybdenum disulfide oil
(onto the camshaft cam lobe and rocker
arm hole)
l
Engine oil
(onto the camshaft bearing)
2. Install:
l
Rocker arms
l
Camshaft
1

3. Apply:
l
Engine oil
(onto the rocker arm shaft)
4. Install:
l
Rocker arm shaft

4 - 45
ENG

CLUTCH AND PRIMARY DRIVEN GEAR
Push rod
1. Inspect:
l
Push rod 1
1

l
Ball
2

Wear/damage/bend
®
Replace.
Primary drive gear
1. Inspect:
l
Primary drive gear
Wear/damage
®
Replace.
EC495000
ASSEMBLY AND INSTALLATION
Push lever
1. Install:
l
Push lever
1
NOTE:
lApply the lithium soap base grease on the oil
seal lip.
lApply the engine oil on the push lever.
Primary drive gear
1. Install:
lStraight key
lPrimary drive gear 1
lWasher 2
lNut (primary drive gear) 3
lPrimary driven gear 4
NOTE:
lInstall the primary drive gear with the stamp
a facing out.
lPlace a folded rag or aluminum plate 5
between the teeth of the primary drive gear
and primary driven gear.
T R..70 Nm (7.0 m · kg, 50 ft · lb)