Honda Z50A Manual page 15

3. Measuring the wear of the valve stem
and valve guide.
Place a dial gauge against the valve
stem and move the valve sideways. and
fore and aft. The amount of wear in
any direction will be indicated on the
gauge (Fig. 19).
Item Standard Value Serviceable Limit
Inlet (
N).0004-0.0012 Replace if over
(0.01-0.03 mm) 0.0032 (0.08 mm)
Exhaust
0.0012-0.002
Replace if over
(0.03-0.05 mm) 0.004 (0.10 mm)
4. Measuring the valve dimension
The valve stem diameter is measured
with a micrometer. (Fig. 20)
Item Standard Value Serviceable Limit
Inlet
0.2148-0.2187 Replace if under
(5.455-5.465mm) 0.2126 (5.40 mm)
Exhaust
0.2070-0.2109 Replace if under
(5.435-5.445mm) 0.2048 (5.38mm)
5. Replacing the valve guide
If the valve guide is worn excessively
and requires replacement. follows the
procedure below.
a. Remove the valve guide from the
cylinder head using the valve guide
remover (Tool No. 07047--04001).
b. Install the new valve guide using the
valve guide driver (Tool No. 07046-
21601). and carefully drive the guide
into the head. The replacement valve
guide should be one that is of an
oversize.
c. After the new valve guide has been
installed, it must be reamed to the
proper finish size using a guide
reamer (Tool No. 07008-24001).
Excercise care when using the reamer
and apply small amount of oil occa-
sionally to lubricate when the reamer
starts to operated hard. pull out the
reamer and remove the metal chip
before continuing to ream.
The standard valve guide diameter is
0.2156-0.2159 (5.475-5.485 mm).
Measurement can be made with
a
cylinder gauge (Fig. 22).
(D
Small dial gauge
®
Valve
Fig. 19
<D
Micrometer
®
Valve
Fig. 20
(D
Valve guide remover
Fig. 21
(D
Valve guide reamer
Fig. 22
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