2003 YAMAHA TTR90 Owners Manual

Page 217 of 340

YAMAHA TTR90 2003  Owners Manual 4 - 23
ENG
CYLINDRE ET PISTON
ZYLINDER UND KOLBEN
Zylinderbohrung “C”47,000–47,005 mm
Konizität “T”0,05 mm
Unrundheit “R”0,05 mm
“C” = Max. D
“T” = (Max. D
1 oder D2) – (Max.

Page 218 of 340

YAMAHA TTR90 2003  Owners Manual 4 - 24
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 rin

Page 219 of 340

YAMAHA TTR90 2003  Owners Manual 4 - 24
ENG
CYLINDRE ET PISTON
ZYLINDER UND KOLBEN
Kolbenring
1. Messen:
Ringnutspiel
Fühlerlehre verwenden. 
Unvorschriftsmäßig → Kolben (kom-
plett) mit Kolbenringen erneuern.
HINWEIS:
Vor der

Page 220 of 340

YAMAHA TTR90 2003  Owners Manual  
4 - 25
ENG
 
CYLINDER AND PISTON 
Piston pin  
1. Inspect: 
 
Piston pin
Blue discoloration/grooves   
→  
 
Replace, then inspect the lubrication
system.
2. Measure: 
 
Piston pin outside diame

Page 221 of 340

YAMAHA TTR90 2003  Owners Manual  
4 - 25
ENG
 
CYLINDRE ET PISTON  
ZYLINDER UND KOLBEN 
Kolbenbolzen  
1. Kontrollieren: 
 
Kolbenbolzen
Blaufärbung/Riefen   
→  
 Erneuern und
Schmiersystem überprüfen.
2. Messen: 
 
Kolbens

Page 222 of 340

YAMAHA TTR90 2003  Owners Manual  
4 - 26
ENG
 
CYLINDER AND PISTON 
2. Position: 
 
Top ring 
 
2nd ring 
 
Oil ring
Offset the piston ring end gaps as
shown. 
a  
Top ring end  
b  
Oil ring end (lower)  
c  
Oil ring end (upper

Page 223 of 340

YAMAHA TTR90 2003  Owners Manual  
4 - 26
ENG
 
2. Positionner: 
 
Segment de feu 
 
Segment d’étanchéité 
 
Segment racleur d’huile 
Décaler les becs de segment comme illus-
tré. 
a 
Becs du segment de feu 
b 
Becs du se

Page 224 of 340

YAMAHA TTR90 2003  Owners Manual  
4 - 27
ENG
 
CLUTCH
CLUTCH 
CRANKCASE COVER (LEFT AND RIGHT) 
Extent of removal: 
1 
 Crankcase cover (left) removal 
2  
 Crankcase cover (right) removal
Extent of removal Order Part name Q’ty Re