Yamaha YZF-R1 98 Service Manual page 161

VALVES AND VALVE SPRINGS
2. Replace:
3. Elim inate:
4. Check:
4 - 25
• valve guide
NOTE:
To ease valve guide rem oval and instal-
lation, and to m aintain the correct fit,
heat the cylinder head to 100 ˚C in an
oven.
a. Rem ove the valve guide w ith a valve
guide rem over 1.
b. Install the new valve guide w ith the
valve guide installer 2 and valve
guide rem over 1.
c. After installing the valve guide, bore
the valve guide w ith a valve guide
ream er 3 to obtain the proper valve-
stem -to-valve-guide clearance.
NOTE:
After replacing the valve guide, reface
the valve seat.
Valve guide remover
Intake (4.0 mm)
90890-04111
Exhaust (4.5 mm)
90890-04116
Valve guide installer
Intake (4.0 mm)
90890-04112
Exhaust (4.5 mm)
90890-04117
Valve guide reamer
Intake
90890-04113
Exhaust
90890-04118
• carbon deposits
(from the valve face and valve seat)
• valve face
Pitting/w ear → Grind the valve face.
• valve stem end
M ushroom shape or diam eter larger
than the body of the valve stem →
Replace the valve.
ENG