Valve Guide Replacement; Service Limits : In : 19 . 67 Mm Ex: 19 . 66 Mm; Service Limits : R: 20.20 Mm - Honda 1988 Z50R Service Manual

CYLINDER HEAD/VAlVES
Measure and reco rd the valve guide 1 .0.
SERVICE LIMITS : IN/EX : 5.03
mm
(0.198 inl
Calculate the stem-ta-guide clearance.
SERVICE LIMITS : IN : 0 .08 mm (0 .003 in)
EX : 0 . 10 mm (O.004 in )
NOTE
If the stem-to-guide clearance exceeds the service limit, de-
termine if a new guide with standard dimensions would bring
the clearance within tolerance. If so, replace guides as neces-
sary and ream to
f it.
II the valve guide is replaced, the valve seat must be refaced.
VALVE GUIDE REPLACEMENT
Heat the cylinder head to 100° _ 1 50 0
e
(212° _300° F) with a hot
plate or oven.
i
To avoid burns, wear heavy glol'es when handling the heated qlinder
head.
CAUTION
Do nOilise a torch
to
heal/he
cy linder
head;
il
may cause warping.
Support the cylinder head and drive out the old guides from the
combustion chamber side of the cylinder head.
TO OL :
Val ve guide driver , 5.0mm: 07942- MA60000
Install a new oversize valve guide from the top of the cylinder
head.
NOTE
When driving in the valve guide, take care not to damage t he
cylinder head .
TOOL :
Valve guide driver , S.Omm: 07942- MA60000
Ream the new valve guide after inst allation.
NOTE
Use cutting oil on the ream er during this operation .
Insert the reamer from the combust ion chamber side of the
head and always rotate the reamer clockwise.
TOOL :
Valve guide reamer, 5.0mm:
07984 - MA6000C
Clean the cylinder head t horoughly to remove any met al particles .
Reface the valve seat (page 6·9).
6-10
- .... ·vAI_VE GUIDE DRIV ER,
VAlVEG UID~
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