2006 YAMAHA TTR50 engine

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 - 29
ENGCLUTCH
CLUTCH
LS
E
E
E
T R..10 Nm (1.0 m • kg, 7.2 ft • Ib)T R..6 Nm (0.6 m •
kg, 4.3 ft • Ib)
T R..70 Nm (7.0 m •
kg, 50 ft • lb)
E
New
E
E
2 3
6
7
8
7
10
9
11
1314
16
25
45
20
20
191817
2728
29
2630
21
2423
22
12 15
31
1
New
T R..5 Nm (0.5 m •
kg, 3.6 ft • Ib)
(3)
Extent of removal: 1 Friction plate and clutch plate removal
2 Clutch housing removal
3 Clutch removal
Extent of removal Order Part name Q ’ty Remarks
CLUTCH REMOVAL
Preparation for removal Brake pedal and footrest assem- bly Refer to
“ENGINE REMOVAL ” section.
1 Clutch adjuster cover 1
2 Clutch adjuster locknut 1
3 Crankcase cover (right) 1
4 Dowel pin 2
5 Gasket 1
6 Clutch adjuster 1
7 Shift guide 2
8 Pawl holder 1
9 Shift arm 1
10 Pressure plate 1
213

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 - 47
ENGENGINE REMOVAL
ENGINE 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:
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 assembly, fuel tank air filter
case cover and air filter case Refer to
“FRONT FENDER, SEAT
ASSEMBLY AND FUEL TANK ” section.
Carburetor Refer to “CARBURETOR ” section.
Muffler Refer to “MUFFLER ” section.
Spark plug cap
Disconnect the AC magneto cou-
plers.
Disconnect the neutral switch
lead.
Starter motor Refer to “ELECTRIC STARTING SYS-
TEM ” section in the CHAPTER 6.

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 - 49
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
9 Engine mounting bolt (rear upper side) 1
10 Engine mounting bolt (rear lower side) 1
11 Engine 1 Refer to “REMOVAL POINTS ”.
1

4 - 50
ENG
REMOVAL POINTS
Engine removal
1. Remove:Engine 1
From left side.
NOTE:
Make sure that the couplers, hoses and cables
are disconnected.1
ASSEMBLY AND INSTALLATION
Engine installation
1. Install: Engine 1
Install the engine from left side.
 Engine mounting bolt (rear lower side) 2
 Engine mounting bolt (rear upper side) 3
 Engine bracket 4
 Bolt (engine bracket) 5
 Engine mounting bolt (front) 6 5
3
2
4
1
6
T R..48 Nm (4.8 m · kg, 35 ft · lb)
T R..30 Nm (3.0 m · kg, 22 ft · lb)
T R..30 Nm (3.0 m · kg, 22 ft · lb)
T R..30 Nm (3.0 m · kg, 22 ft · lb)
ENGINE REMOVAL

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.