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Kawasaki Z250 1981 Service Manual Page 130

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124 MAINTENANCE-ENGINE
Insert
a new valve
into
the
guide
and set a
dial
gauge
against
the stern perpend icular
to
it
as close
as possible
to
the
cylinder
head
mating surface.
Move
the
stem
back
and
forth
to measure
valve/valve
guide clearance.
Repeat
the
measuremen
t
in
a
direction
at a
right
angle
to
the
first.
If the
reading
exceeds
the
service
limit,
replace
th
e
guide.
NOTE:
The
reading
is
not actual valve/valve
gu ide clear-
ance because
the
measuring
point is above the guide.
A.
Valve
Table H21
Valve/Valve Guide Clearance
(Wobble Method)
Standard
Service
Limit
0.024-0.089 mm
0.24
mm
Valve
seat repair
The valve
must seat
in
the
valve
seat
evenly around
the
circumference
over
the
specified
c1rea.
If
the
seat
is
too
wide, the
seating
pressure
per
unit o
r
area
is re-
duced, wh ich
may
resu
lt
in
compression leakage and
carbon accumulation
on
the
seating
surface.
If
the
seating
area
is too
narrow, heat tra,nsfer
from
the
valve
is reduced
and
the valve
will overheat and
warp.
Uneven
seating
or seat damage
will
cause
compression
leakage.
Valve
Seating Width
Table H22
Valve Seating Width
Standard
0.3 5-0.65
mm
To
determine
whether
or
not
the
valve
seat
requires
rep
air,
first remove
the
valve,
apply
mach inist's dye
to
the valve
seat, and
then
use a
lap
per
to
tap the
valve
lightly
into place.
Remove
the
valve,
and
note
where
the
dye adheres
to
the valve
seating
surface.
The
valve
seating surface
should
be in
the middle
of the
valve
face
(Fig.
H31).
The
distribu
tion
of the dye
on
the
seating
surface gives an
indication
of seat
condition (Fig.
H34)
.
NOTE
:
The valve and
valve
gu ide must
be
in
good
condition
before
this check wil
l
give
an
accurate
in-
dication of
valve
seat condition.
A. Valve Seating Surface
A valve
seat
which
requires
repair
is
cut
with a
se
t
of
valve
seat
cutters.
First,
cut
the
seating
surface
of the valve seat
with
the
45° cutter.
Cut
only
the
amoun
t necessary
to make
a
good
surface;
overcutting
will
reduce the
valve clear-
ance,
possibly
making
it
no longer
adjustable.
Next, use the 75° cutter
to
cut the
surface outside
the
seating
su
rface.
Cut
these
two
surfaces
so that
the
seating surface will
have the specified wid
th.
A. Valve Cutter
After
cutting, lap
the
valve to properly
match
the
valve and
valve
seat
surfaces.
Start
off
with
coarse
lapp
ing
compound, and
finish
with fi
ne
compou
nd.

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Kz350 1981

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