Piston Rings - Yamaha SZR 660 Service Manual

INSPECTION
AND
REPAIR
Third stage
Calculate the ptston-cyitnderclearance according
to
the following formula.
Piston-cylinder
clearance =
Cylinder boring
"C"-
Piston
skirt
diameter "P"
Piston-cylinder clearance:
0.050-0.070
mm
Maximum
limit:
0.15
mm
'
vi^V)J\V^
> J
^V* +&+<
if
the
measurements
are out of tolerance, rebore
or
replace the
cylinder,
and replace
the piston
and
piston
ring
as a
set.
r * * *
* w *
* *
INSPECTION
AND
REPAIR
ENG
%•
PISTON RINGS
1.
Measure:
•
Lateral
clearance
of
rings
Use
a thickness gauge.
Out
of specification -*
Replace
piston
and
piston ring
as
a set.
NOTE:
_^^__
Before measuring
lateral
clearance, remove
car-
bon
deposits
from
the piston
ring
seats
and
from the
rings
themselves.
s
Piston
ring lateral
clearance:
Upper
ring
0.04
~
0.08
mm
Lower
ring 0.03
-
0.07
mm
i
_
* —
fc
- *^ I
j®
^^-^'i
rf'^^^^^i*^
V
/
*•
2.
Position:
•
Ring
(into cylinder)
NOTE:
Fit
each ring
into
the cylindsrand push
it
to
about20
mm
from the top edge
of the cylinder.
Push
the ring
into the cylinder with the piston so that
it is
perfectly
perpendicular
to the cylinder axis.
(a)
20
mm
3.
Measure:
• Ring
tip
port
Out
of specification ->
Replace.
NOTE:
. . . .
It
is
impossible
to
measure
the
oil
scraper
tip port.
I!
the
oil
scraper
port
appears
too large,
replace
alt
three rings as
a set.
<%
Piston ring tip port
(fitted
into cylinder)
Upper
ring
0.30
~
0.45
mm
Lower
ring
0.30-0.45
mm
Oil
scraper
(tracks)
0.20
~
0.70
mm
4-39 4-40