2004 YAMAHA TTR125 Piston and rings

CHAPTER 3
REGULAR INSPECTION
AND ADJUSTMENTS
MAINTENANCE INTERVALS ...................3-1
PRE-OPERATION INSPECTION
AND MAINTENANCE ................................3-3
ENGINE ......................................................3-4
CHASSIS .................................................3-15
ELECTRICAL ...........................................3-34
CHAPTER 4
ENGINE
SEAT, FUEL TANK
AND SIDE COVERS ..................................4-1
MUFFLER ..................................................4-2
CARBURETOR ..........................................4-3
CYLINDER HEAD ....................................4-12
CAMSHAFT AND ROCKER ARMS ........4-20
VALVES AND VALVE SPRINGS ............4-24
CYLINDER AND PISTON ........................4-32
CLUTCH AND PRIMARY DRIVEN
GEAR .......................................................4-40
OIL PUMP ................................................4-49
KICK AXLE AND SHIFT SHAFT .............4-53
CDI MAGNETO
(TT-R125/TT-R125LW) ............................4-58
CDI MAGNETO AND STARTER
CLUTCH (TT-R125E/TT-R125LWE) .......4-61
ENGINE REMOVAL .................................4-66
CRANKCASE, CRANKSHAFT
AND BALANCER ....................................4-70
TRANSMISSION, SHIFT CAM
AND SHIFT FORK ...................................4-78

1 - 12
GEN
INFO
FUEL
Use regular gasoline. Always use fresh, name
brand gasoline.
WARNING
Do not overfill the fuel tank. Avoid spilling
fuel on the hot engine. Do not fill the fuel
tank above the bottom of the filler tube 1
as shown in the illustration or it may over-
flow when the fuel heats up later and
expands.
aFuel level
CAUTION:
Use only unleaded gasoline. The use of
leaded gasoline will cause severe damage
to the engine internal parts such as valves,
piston rings, and exhaust system, etc.
Recommended fuel:
For USA, AUS and NZ:
Unleaded gasoline only
For CDN and EUROPE:
Regular unleaded gasoline
only
For ZA:
Regular gasoline
Fuel tank capacity:
Total:
6.6 L (1.45 lmp gal, 1.74 US gal)
Reserve:
1.9 L (0.42 Imp gal, 0.5 US gal)
FUEL

SPEC
2 - 10
MAINTENANCE SPECIFICATIONS
Piston:
Piston to cylinder clearance 0.020 ~ 0.026 mm
(0.0008 ~ 0.0010 in)0.15 mm
(0.0059 in)
Piston size “D”53.977 ~ 53.996 mm
(2.1251 ~ 2.1258 in)----
Piston over size (2nd) 54.5 mm (2.1457 in) ----
(4th) 55.0 mm (2.1654 in) ----
Measuring point “H”5 mm (0.20 in) ----
Piston off-set 0.5 mm (0.0197 in) ----
Piston pin bore inside diameter 15.002 ~ 15.013 mm
(0.5906 ~ 0.5911 in)15.043 mm
(0.5922 in)
Piston pin outside diameter 14.991 ~ 15.000 mm
(0.5902 ~ 0.5906 in)14.971 mm
(0.5894 in)
Piston rings:
Top ring
Type Barrel ----
Dimensions (B × T) 1.0 × 2.1 mm (0.04 × 0.08 in) ----
End gap (installed) 0.15 ~ 0.30 mm
(0.006 ~ 0.012 in)0.4 mm
(0.016 in)
Side clearance (installed) 0.035 ~ 0.090 mm
(0.0014 ~ 0.0035 in)0.12 mm
(0.0047 in)
2nd ring
Type Taper ----
Dimensions (B × T) 1.0 × 2.1 mm (0.04 × 0.08 in) ----
End gap (installed) 0.30 ~ 0.45 mm
(0.012 ~ 0.018 in)0.55 mm
(0.022 in)
Side clearance 0.020 ~ 0.060 mm
(0.0008 ~ 0.0024 in)0.12 mm
(0.0047 in)
Oil ring
Dimensions (B × T) 2.0 × 2.2 mm (0.08 × 0.09 in) ----
End gap (installed) 0.20 ~ 0.70 mm (0.01 ~ 0.03 in) ----Item Standard Limit
H
D
T
B
B
T
B
T

4 - 33
ENGCYLINDER AND PISTON
REMOVAL POINTS
Piston
1. Remove:
Piston pin clips 1
Piston pin 2
Piston 3
NOTE:
Before removing the piston pin clip, cover the
crankcase opening with a clean towel or rag
to prevent the clip from falling into the crank-
case cavity.
Before removing each piston pin, deburr the
clip groove and pin hole area. If the piston
pin groove is deburred and the piston pin is
still difficult to remove, use the piston pin
puller 4.
CAUTION:
Do not use a hammer to drive the piston
pin out.
Piston ring
1. Remove:
Piston rings
NOTE:
Spread the end gaps apart while at the same
time lifting the piston ring over the top of the
piston crown, as shown in the illustration.
Piston pin puller set:
YU-1304/90890-01304
INSPECTION
Cylinder and piston
1. Inspect:
Cylinder and piston walls
Vertical scratches → Replace cylinder
and piston.

4 - 34
ENGCYLINDER AND PISTON
2. Measure:
Piston-to-cylinder clearance
Piston-to-cylinder clearance measure-
ment steps:
1st step:
Measure the cylinder bore “C” with the cyl-
inder bore gauge.
NOTE:
Measure the cylinder bore “C” in parallel to
and at right angles to the crankshaft. Then,
find the average of the measurements.
Cylinder bore “C”54.000 ~ 54.019 mm
(2.126 ~ 2.127 in)
Taper limit “T”0.05 mm (0.002 in)
Out of round “R”0.05 mm (0.002 in)
“C” = maximum of D
1 ~ D6
“T” = maximum of D
1, or D2 –
maximum of D
5 or D6
“R” = maximum of D
1, D3 or D5 –
minimum of D
2, D4 or D6
If out of specification, replace the cylinder,
and replace the piston and piston rings as
set.
2nd step:
Measure the piston skirt diameter “P” with
a micrometer.
a5 mm (0.20 in) from the piston bottom edge.
Piston size P
Standard53.977 ~ 53.996 mm
(2.1251 ~ 2.1258 in)
If out of specification, replace the piston
and piston rings as a set.
3rd step:
Calculate the piston-to-cylinder clearance
with following formula.
Piston-to-cylinder clearance =
Cylinder bore “C” –
Piston skirt diameter “P”
Piston-to-cylinder clearance:
0.020 ~ 0.026 mm
(0.0008 ~ 0.0010 in)
: 0.15 mm (0.006 in)

4 - 35
ENGCYLINDER AND PISTON
If out of specification, replace the cylinder,
and replace the piston and piston rings as
a set.
Piston pin
1. Inspect:
Piston pin
Blue discoloration/grooves → Replace,
then inspect the lubrication system.
2. Measure:
Piston pin-to-piston clearance
Measurement steps:
Measure the piston pin outside diameter
a.
If out of specification, replace the piston
pin.
Outside diameter (piston pin):
14.991 ~ 15.000 mm
(0.5902 ~ 0.5906 in)
: 14.971 mm (0.5894 in)
Measure the piston inside diameter b.
If out of specification, replace the piston.
Inside diameter (piston):
15.002 ~ 15.013 mm
(0.5906 ~ 0.5911 in)
: 15.043 mm (0.5922 in)

4 - 36
ENGCYLINDER AND PISTON
Piston ring
1. Measure:
Ring side clearance
Use a feeler gauge.
Out of specification → Replace the pis-
ton and rings as a set.
NOTE:
Clean carbon from the piston ring grooves and
rings before measuring the side clearance.
Side clearance:
Standard
Top
ring0.035 ~ 0.090 mm
(0.0014 ~ 0.0035 in)0.12 mm
(0.0047 in)
2nd
ring0.020 ~ 0.060 mm
(0.0008 ~ 0.0024 in)0.12 mm
(0.0047 in)
2. Position:
Piston ring
(in cylinder)
NOTE:
Insert a ring into the cylinder and push it
approximately 40 mm (1.57 in) into the cylin-
der. Push the ring with the piston crown so that
the ring will be at a right angle to the cylinder
bore.
a40 mm (1.57 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.
End gap:
Standard
Top
ring0.15 ~ 0.30 mm
(0.006 ~ 0.012 in)0.4 mm
(0.016 in)
2nd
ring0.30 ~ 0.45 mm
(0.012 ~ 0.018 in)0.55 mm
(0.022 in)
Oil ring0.20 ~ 0.70 mm
(0.01 ~ 0.03 in)—

4 - 36
ENG
CYLINDRE ET PISTON
ZYLINDER UND KOLBEN
Kolbenring
1. Messen:
Ringnutspiel
Fühlerlehre verwenden.
Nicht im Sollbereich → Kolben und Kol-
benringe komplett erneuern.
HINWEIS:
Kohleablagerungen aus den Kolbenringnuten
und von den Kolbenringen entfernen, bevor
das Ringnutspiel gemessen wird.
Ringnutspiel:
Standard

1. Kom-
pressi-
onsring0,035–0,090 mm
(0,0014–0,0035 in)0,12 mm
(0,0047 in)
2. Kom-
pressi-
onsring0,020–0,060 mm
(0,0008–0,0024 in)0,12 mm
(0,0047 in)
2. Einsetzen:
Kolbenring
(in den Zylinder)
HINWEIS:
Einen Kolbenring etwa 40 mm (1,57 in) tief in
den Zylinder schieben. Den Kolbenring so mit
dem Kolbenboden in den Zylinder schieben,
daß sich der Ring im rechten Winkel zur Zylin-
derbohrung befindet.
a40 mm (1,57 in)
3. Messen:
Stoßspiel
Nicht im Sollbereich→ Erneuern.
HINWEIS:
Das Stoßspiel des Expanderrings des Ölab-
streifrings kann nicht gemessen werden. Falls
die Abstreifringe des Ölabstreifrings übermäßi-
ges Stoßspiel aufweisen, müssen alle drei
Ringe erneuert werden.
Ringnutspiel:
Standard

1. Kom-
pressi-
onsring0,15–0,30 mm
(0,006–0,012 in)0,4 mm
(0,016 in)
2. Kom-
pressi-
onsring0,30–0,45 mm
(0,012–0,018 in)0,55 mm
(0,022 in)
Ölab-
streifring0,20–0,70 mm
(0,01–0,03 in)—
Segment de piston
1. Mesurer:
Jeu latéral de segment
Utiliser une cale d’épaisseur.
Hors spécifications → Remplacer à la fois
le piston et les segments.
N.B.:
Avant de mesurer le jeu latéral, éliminer la cala-
mine des gorges de segment et des segments.
Jeu latéral:
Standard
Segment
de feu0,035 à 0,090 mm
(0,0014 à 0,0035 in)0,12 mm
(0,0047 in)
Segment
d’étan-
chéité0,020 à 0,060 mm
(0,0008 à 0,0024 in)0,12 mm
(0,0047 in)
2. Positionner:
Segment de piston
(dans le cylindre)
N.B.:
Placer un segment dans le cylindre et l’enfoncer
d’environ 40 mm (1,57 in). Pousser le segment
avec la couronne du piston pour le placer à angle
droit par rapport à l’alésage du cylindre.
a40 mm (1,57 in)
3. Mesurer:
Écartement des becs de segments
Hors spécifications → Remplacer.
N.B.:
II est impossible de mesurer l’écartement des becs
de la bague extensible du segment racleur d’huile.
Si les rails du segment racleur d’huile sont sérieu-
sement écartés, remplacer les trois segments.
Écartement des becs:
Standard
Segment
de feu0,15 à 0,30 mm
(0,006 à 0,012 in)0,4 mm
(0,016 in)
Segment
d’étan-
chéité0,30 à 0,45 mm
(0,012 à 0,018 in)0,55 mm
(0,022 in)
Segment
racleur
d’huile0,20 à 0,70 mm
(0,01 à 0,03 in)—