Oil YAMAHA TTR50 2006 Service Manual

4 - 26
ENGCYLINDER AND PISTON
Piston ring
1. Measure:Ring side clearance
Use a thickness gauge.
Out of specification → Replace the piston
and rings as a set.
NOTE:
Clean carbon from the piston ring grooves and
rings before measuring the side clearance.
2. Position: Piston ring
(in cylinder)
NOTE:
Insert a ring into the cylinder and push it
approximately 10 ~ 15 mm (0.39 ~ 0.59 in) into
the cylinder. Push the ring with the piston
crown so that the ring will be at a right angle to
the cylinder bore.
a 10 ~ 15 mm (0.39 ~ 0.59 in)
3. Measure:
Ring end gap
Out of specification → Replace.
NOTE:
You cannot measure the end gap on the
expander spacer of the oil control ring. If the oil
control ring rails show excessive gap, replace
all three rings.
Thickness gauge:
YM-34483/90890-03079
Side clearance
Standard Limit
Top ring 0.020 ~ 0.070 mm
(0.0008 ~ 0.0028 in) 0.12 mm
(0.005 in)
2nd ring 0.020 ~ 0.060 mm
(0.0008 ~ 0.0024 in) 0.12 mm
(0.005 in)
End gap
Standard Limit
Top ring 0.10 ~ 0.25 mm
(0.004 ~ 0.010 in) 0.50 mm
(0.020 in)
2nd ring 0.15 ~ 0.30 mm
(0.006 ~ 0.012 in) 0.65 mm
(0.026 in)
Oil ring 0.20 ~ 0.70 mm
(0.008 ~ 0.028 in) —

4 - 27
ENGCYLINDER AND PISTON
Piston pin
1. Inspect:Piston pin
Blue discoloration/grooves →
Replace, then inspect the lubrication sys-
tem.
2. Measure: Piston pin outside diameter
 Piston pin bore inside diameter
ASSEMBLY AND INSTALLATION
Piston
1. Install: Piston rings
(onto the piston)
NOTE:
 Be sure to install the piston rings so that the
manufacturer ’s marks or numbers are
located on the upper side of the rings.
 Lubricate the piston and piston rings liberally
with engine oil.
Measurement steps:

Measure the piston pin outside diameter
a .
If out of specification, replace the piston
pin.
Outside diameter (piston pin): 11.996 ~ 12.000 mm
(0.4723 ~ 0.4724 in)
:11.976 mm (0.4715 in)
 Measure the piston inside diameter b.
If out of specification, replace the piston.
Inside diameter (piston): 12.002 ~ 12.013 mm
(0.4725 ~ 0.4730 in)
: 12.043 mm (0.4741 in)

4 - 28
ENGCYLINDER AND PISTON
2. Position:Top ring
 2nd ring
 Oil ring
Offset the piston ring end gaps as shown.
a Top ring
b Upper oil ring rail
c Oil ring expander
d Lower oil ring rail
e 2nd ring
f 20 mm (0.79 in)
È Intake side
3. Install:
Piston 1
 Piston pin 2
 Piston pin clips 3
NOTE:
Apply engine oil onto the piston pin, piston
ring and piston.
 Be sure that the arrow mark
a on the piston
points to the exhaust side of the engine.
 Before installing the piston pin clip, cover the
crankcase with a clean rag to prevent the
piston pin clip from falling into the crankcase.
4. Lubricate: Piston
 Piston rings
 Cylinder
NOTE:
Apply a liberal coating of engine oil.
Cylinder
1. Install:
Dowel pins
 Gasket
 Cylinder 1
NOTE:
Install the cylinder with one hand while com-
pressing the piston rings with the other hand.
CAUTION:
 Be careful not to damage the timing chain
damper during installation.
 Pass the timing chain through the timing
chain cavity.
e a
ff
d cb120
˚
120 ˚ 120˚
È
New
1
New

4 - 39
ENGOIL PUMP
OIL PUMP
Extent of removal: 1 Oil pump removal
2 Oil strainer removal
3 Oil pump disassembly
Extent of removal Order Part name Q ’ty Remarks
OIL PUMP REMOVAL AND DIS-
ASSEMBLY
Preparation for removal Primary drive gear and primary driven gear Refer to
“CLUTCH ” section.
Shift shaft Refer to “SHIFT SHAFT ” section.
1 Oil pump assembly 1
2 Gasket 1
3 Oil pump drive gear 1
4 Oil strainer 1
5 Circlip 1
6 Oil pump driven gear 1
7Pin 1
8 Oil pump cover 1
2
1
3

4 - 40
ENGOIL PUMP
Extent of removal Order Part name Q’ty Remarks
9 Oil pump drive shaft 1
10 Pin 1
11 Inner rotor 1
12 Outer rotor 1
13 Rotor housing 1
3

4 - 41
ENGOIL PUMP
INSPECTION
Oil pump
1. Measure:Inner-rotor-to-outer-rotor tip clearance a
(between the inner rotor 1 and the outer
rotor 2)
 Outer-rotor-to-oil-pump housing clear-
ance b
(between the outer rotor 2 and the rotor
housing 3)
Out of specification → Replace the oil
pump assembly.
 Oil-pump-housing-to-inner-and-outer-
rotor clearance c (between the rotor
housing 3 and the rotors 1 2 )
Out of specification → Replace the oil
pump assembly.
Inner-rotor-to-outer-rotor tip
clearance a:
0.15 mm or less
(0.0061 in or less)
: 0.20 mm (0.0079 in)
Outer-rotor-to-oil-pump housing
clearance b:
0.07 mm
(0.0028 in)
: 0.15 mm (0.0059 in)
Oil-pump-housing-to-inner-and-
outer-rotor clearance c:
0.06 ~ 0.10 mm
(0.0024 ~ 0.0039 in)
: 0.17 mm (0.0067 in)
Rotary filter and oil strainer
1. Inspect:
Oil strainer 1
Damage → Replace.
2 Upper side
3 Lower side

4 - 42
ENGAC MAGNETO AND STARTER CLUTCH
AC MAGNETO AND STARTER CLUTCH
È Stake
Extent of removal: 1 Crankcase cover (left) removal
2 Pickup coil/stator removal
3 Rotor removal
4 Starter clutch/wheel gear removal
Extent of removal Order Part name Q ’ty Remarks
AC MAGNETO AND STATOR
REMOVAL
Preparation for removal Seat assembly Refer to “FRONT FENDER, SEAT
ASSEMBLY AND FUEL TANK ” section.
1 Crankcase cover (left) 1
2 Dowel pin 2
3 Gasket 1
4 AC magneto coupler 2
5 Neutral switch lead 1
6 Pickup coil/stator assembly 1
7 Rotor nut 1 Use special tool.
Refer to “REMOVAL POINTS ”.
8 Rotor 1
9 Woodruff key 1
21
3
4

4 - 46
ENGAC MAGNETO AND STARTER CLUTCH
3. Install:Spring 1
 Spring cap 2
 Pin 3
4. Install: Shim 1
 Starter wheel gear 2
 Starter idle gear 3
 Shaft 4
NOTE:
Apply the molybdenum disulfide oil on the
starter wheel gear inner circumference.
 Apply the engine oil on the starter idle gear
inner circumference and on the shaft outer
circumference.
1 2
3
12
3
5. Install:
Woodruff key 1
 Rotor 2
NOTE:
Clean the tapered portion of the crankshaft
and the rotor hub.
 When installing the rotor, make sure the
woodruff key is properly seated in the key
way of the crankshaft.
6. Tighten: Rotor nut 1
NOTE:
Tighten the rotor nut 1 while holding the
rotor 2 with a sheave holder 3.
 Do not allow the sheave holder to touch the
projection on the rotor.
7. Install: Crankcase cover (left)
NOTE:
 Pass the starter motor lead 1 and neutral
switch lead 2 into the crankcase cover
groove as shown.
 Fasten the starter motor lead with the clamp 3.
Sheave holder:
YS-01880-A/90890-01701
T R..48 Nm (4.8 m · kg, 35 ft · lb)
3
1
2

4 - 48
ENGENGINE REMOVAL
(4)
NewNew
LS
T R..30 Nm (3.0 m • kg, 22 ft • Ib)
T R..30 Nm (3.0 m •
kg, 22 ft • Ib)
T R..30 Nm (3.0 m •
kg, 22 ft • Ib)
T R..30 Nm (3.0 m •
kg, 22 ft • Ib)
T R..48 Nm (4.8 m •
kg, 35 ft • Ib)
T R..7 Nm (0.7 m •
kg, 5.1 ft • Ib)
T R..10 Nm (1.0 m • kg, 7.2 ft • Ib)
(3)
10
4
1 6
2
9
3
11
7
5 8
Extent of removal Order Part name Q
’ty Remarks
Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT ”
section in the CHAPTER 3.
1 Drive sprocket cover 1
2 Drive sprocket 1
3 Shift pedal 1
4 Brake pedal 1
5 Footrest 1
6 Crankcase breather hose 1
7 Engine mounting bolt (front upper side) 1
8 Engine bracket 1
1

4 - 51
ENGCRANKCASE AND CRANKSHAFT
CRANKCASE AND CRANKSHAFT
E
T R..10 Nm (1.0 m • kg, 7.2 ft • Ib)
T R..10 Nm (1.0 m •
kg, 7.2 ft • Ib)
LT
4
4 3
4
4
5 6
7
9
8
8
12
5 6
4
Extent of removal Order Part name Q ’ty Remarks
CRANKCASE SEPARATION
AND CRANKSHAFT REMOVAL
Preparation for removal Seat assembly and fuel tank
Exhaust pipe
Air filter case and bottom cover Refer to “FRONT FENDER, SEAT
ASSEMBLY AND FUEL TANK ” section.
Carburetor Refer to “CARBURETOR ” section.
Drain the engine oil. Refer to “ENGINE OIL REPLACEMENT ”
section in the CHAPTER 3.
Drive sprocket Refer to “ENGINE REMOVAL ”.
Cylinder head Refer to “CYLINDER HEAD ” section.
Cylinder and piston Refer to “CYLINDER AND PISTON ” sec-
tion.
Primary driven gear Refer to “CLUTCH ” section.