Timing YAMAHA TTR125 2003 Owners Manual

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

3 - 11
INSP
ADJ
VALVE CLEARANCE INSPECTION AND ADJUSTMENT
VALVE CLEARANCE INSPECTION AND
ADJUSTMENT
NOTE:
The valve clearance should be adjusted
when the engine is cool to the touch.
The piston must be at Top Dead Center
(T.D.C.) on compression stroke to check or
adjust the valve clearance.
1. Remove:
Seat
Fuel tank
Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section in the CHAPTER 4. Adjustment steps:
Adjust the pilot air screw.
Refer to “PILOT AIR SCREW ADJUST-
MENT” section.
Turn the throttle stop screw 1 until the
specified engine idling speed.
To increase idling speed →
Turn the throttle stop screw 1 in a.
To decrease idling speed →
Turn the throttle stop screw 1 out b.
Inductive tachometer:
YU-8036-B/90890-03113
Engine idling speed:
1,300 ~ 1,500 r/min
2. Remove:
Spark plug
Intake tappet cover 1
Exhaust tappet cover 2
O-ring
3. Remove:
Timing mark accessing screw 1
Crankshaft end accessing screw 2
O-ring

3 - 13
INSP
ADJ
VALVE CLEARANCE INSPECTION AND ADJUSTMENT
Measure the valve clearance.
If the clearance is incorrect, repeat above
steps until specified clearance is obtained.
6. Install:
O-ring 1
Crankshaft end accessing screw 2
Timing mark accessing screw 3
NOTE:
Apply the lithium soap base grease on the O-
rings.
New
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
7. Install:
O-ring 1
Exhaust tappet cover 2
Intake tappet cover 3
NOTE:
Apply the lithium soap base grease on the O-
rings.
8. Install:
Spark plug
Fuel tank
Seat
Refer to “SEAT, FUEL TANK AND
SIDE COVERS” section in the CHAP-
TER 4.
New
T R..18 Nm (1.8 m · kg, 13 ft · lb)
T R..18 Nm (1.8 m · kg, 13 ft · lb)
T R..13 Nm (1.3 m · kg, 9.4 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)

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 - 13
ENGCYLINDER HEAD
CYLINDER HEAD
Extent of removal:1 Cylinder head removal
Extent of removal Order Part name Q’ty Remarks
CYLINDER HEAD REMOVAL
1 Bolt (camshaft sprocket) 1
Refer to “REMOVAL POINTS”. 2 Bolt (timing chain tensioner cap) 1
3 Timing chain tensioner 1
4 Gasket 1
5 Camshaft sprocket 1
6 Cylinder head 1
7 Dowel pin 2
8Gasket
1
1

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.

4 - 17
ENGCYLINDER HEAD
3. Install:
Timing chain
Camshaft sprocket
4. Install:
Washer
Bolt (camshaft sprocket)
NOTE:
Temporarily tighten the bolt (camshaft sprocket)
at this point. Installation 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.
Align the match mark c on the camshaft
sprocket with the stationary pointer d on
the cylinder head.
Fit the timing chain 1 onto camshaft
sprocket 2 and install the camshaft
sprocket on the camshaft.
NOTE:
When installing the camshaft sprocket, keep
the timing chain as tense as possible on the
exhaust side.
CAUTION:
Do not turn the crankshaft during instal-
lation of the camshaft. Damage or
improper valve timing will result.
Remove the safety wire from the timing
chain.

4 - 18
ENGCYLINDER HEAD
5. Install:
Timing chain tensioner
6. Turn:
Crankshaft
Counterclockwise several turns
7. Check:
Rotor “I” mark
Align with the crankcase stationary
pointer.
Camshaft match mark
Align with the cylinder head stationary
pointer.
Out of alignment → Adjust. Installation steps:
While pressing the tensioner rod lightly
with fingers, use a thin screwdriver and
wind the tensioner rod up fully clockwise.
With the rod fully wound, install the gasket
1 and the chain tensioner 2, and tighten
the bolts 3 to the specified torque.
T R..
Bolt (chain tensioner):
10 Nm (1.0 m • kg, 7.2 ft • lb)
Release the screwdriver, check the ten-
sioner rod to come out and tighten the
gasket 4 and the cap bolt 5 to the speci-
fied torque.
T R..
Cap bolt (timing chain tensioner):
8 Nm (0.8 m • kg, 5.8 ft • lb)
8. Tighten:
Bolt 1
NOTE:
Tighten the bolt while holding the rotor nut with
a wrench.
T R..20 Nm (2.0 m · kg, 14 ft · lb)

4 - 19
ENGCYLINDER HEAD
9. Check:
Valve clearance
Out of specification → Adjust.
Refer to “VALVE CLEARANCE
INSPECTION AND ADJUSTMENT”
section in the CHAPTER 3.
10. Apply:
Engine oil
On camshaft.
11. Install:
Tappet cover 1
Cylinder 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:
Timing mark accessing screw 1
Crankshaft 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:
Spark plug
Engine bracket
T R..13 Nm (1.3 m · kg, 9.4 ft · lb)
T R..40 Nm (4.0 m · kg, 29 ft · lb)