Table of Contents
Advertisement
ENGINE MAINTENANCE -
Piston and Piston Ring Maintenance (GP292B)
Remedies:
(1)
If
any
pisto
n
ring is fou11d stuck,
poor
seali
ng
will
resu It.
•
(2)
If the
cylind
er
wall is scuffed,
poor
sealing wil
l
result
as
in
the case
of t
he
piston ring being stuck.
In
the
above
two
cases,
the piston ring
should be replaced with
a
11ew
one, and at
the
same
time, the
cylinder
wall
shou
ld be
checked
for scratches.
(3)
Whether
the contact between
the
piston
ring
and
the
cylinder
wal
I
is
good or
not
wi
11
have
a
great
effect on
sea
ling.
Th
e
enti
re
area of the
piston
ring
face
must
be
in
tight
con
t
ac
t with
the
cylinder wall. If
excess
wear
is
found
on the
upper or
t
he lower half
of
the
p
iston
ri
ng
face,
the
piston ring groove is considered to
be
worn
unevenly,
caus
ing
the
r
ing to twist.
(See
Fig. 8-48)
If
imit
ation piston
rings (other t han genu ine Yamaha
parts) are
used, such defects as mentioned
in
(3) and
(4)
above may easi
ly
occu
r,
and
in
the
worst
case,
seri
o us
engine
troubles may
resu
It.
(4}
When
a
good sea
I between the
piston
r
i
ng bottom
and
the
ring
groove bottom is
noticed, the
piston
ring
is
co
nsidered
to smoothly
slide
in and out
on the ring
groove bot
tom
in
a
correct manner.
8-5-4
Before
repla
ci
r1g
the
piston ring,
remove carbon accumu
la-
t
ions from the gap between
t
he ring and the groove. The
piston
r
i
ng
must be
insta
lled so
that
the locating
pin
knocked
in the
groove
is
between
both
ends of
the
ring
as
illustrated
.
This is
the most vital
requirement to be
observed
when the
piston
is inserted
into the cylinder.
-
-
-
-
-
-
- -
-
-
-
-
-
-
-
- -
-
-
-
Fig
.
8-47
--
.
-
-
--
--
.
-
-
-
- - -
-
-
-
-
-
-
-
- ..
--
-
-
8-5-5
•
The up and down movement of
the piston ring in
the
piston
groove can be
calculated
from
the side
clearance
as
illustrated.
Th
is
side
clearance
is
created
by wear on the
ring bottom.
If
the side
clearance
is
measured more than
0 .0008''
(0.2
mm), the ring should
be replaced.
The
illustration shows
the
sectional
view
of
a new piston ring
installed
in
the ring groove.
Piston ring
'
I
(Side
cleara
0.0003"
(0.06
mm)
Measure
w
feeler gaug
nee)
ith
e
Fig
.
8-48
Piston
r
'
~
:
I
-
•
-73-
•
•
•
.
•
Hide quick links:
Advertisement
Table of Contents
