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3-3 INSPECTION AND REPAIR
A. Cylinder Head Cover
Place head cover o n a surface plate. There should be
no
warpage. Correct b y re-surfacing as follows:
Place #400 o r #600 grit w et sandpaper o n surface
plate and re-surface head cover using a figure-eight
sanding pattern. Rotate head cover several times to
avoid removing t o o much material fr o m one side.
B. Cylinder Head
1. Remove spark plugs.
2. Remove valves.
3. Using a rounded scraper, remove carbon de-
posits f r o m combustion chamber. Take care
to avoid damaging spark plug threadsand valve
seats. Do n o t use a sharp instrument. Avoid
scratching the aluminum.
4. Place on a surface plate. There should be n o
warpage. Correct b y re-surfacing as follows:
Place #400 o r #600 grit we t sandpaper o n sur-
face plate and re-surface head using
eight sanding pattern. Rotate head several
times t o avoid removing t o o much material
fr o m one side.
C.
Valve, Valve Guide and Valve Seat
1. Valve stem wear must be measured and then
combined w i t h valve guide measurements t o
guide clearance. This clearance must be w i t h i n
tolerances. I f it exceeds the ma x imu m limit,
then replace either o r b o th valve and guide, as
.
necessary
Intake
Exhaust
2. Valve stem end
Inspect end o f valve stem. I f the end appears
t o be "mushroomed" o r has a larger diameter
than the rest of the stem, the valve, valve
guide, and oil seal should be replaced.
3. Tu r n valve o n a "V" block and measure the
amount o f stem run ou t w i t h a dial gauge. If
it exceeds the maximum limit, replace the
valve.
figure-
a
4. Valve guide and valve o il seal replacement
I f o il leaks in to the cylinder through a valve
due to a w o rn valve guide, o r i f a valve i s re-
placed, the valve guide should also be replaced.
NOTE: The valve o il seal should be replaced
whenever a valve i s removed o r replaced.
a. Measure valve guide inside diameter w i t h a
small bore gauge. I f it exceeds the limit, re-
place w i t h an oversize valve guide.
I
Guide diameter (I.D.): 7.01-7.02mm 7.10mm
b. To ease guide removal and reinstallation, and
t o maintain the correct interference fit, heat
the head to 100°C (212°F). Use an oven to
avoid any possibility o f head warpage due t o
uneven heating.
c. Use the appropriate shouldered punch (special
to o l) t o drive the old guide o u t and drive the
new guide in.
NOTE:
o-ring should also be replaced.
.020-.041mm
(.0008~.0016")
.035-.059mm
(.0014~.0023")
Maximum Valve Stem Ru nou t:
.03mm (.0012")
(.276-.277")
When a valve guide is replaced, the
0.10 mm
(.004")
0.12mm
(.005")
I
(0.280')
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