Suzuki GS-1000 Service Manual page 164

ELECTRICAL
SYSTEM
Remove the plug and inspect the insulator.
If
the insulator is a light brown color.
it
is accep-
table. If
It
is blackened by
carbon. it
should be
replaced by
a
hot type
NGK
B7ES
or NIPPON
DENSO W22ES and if baked white, by NGK
R9ES
or NIPPON DENS0 W27ES.
Plugs with high heat range number
are used for
high speed
running. These plugs are designed to
be sufficiently cooled
to
prevent overheating and
are called cold type plugs. If
a plug with too
high a
heat value is used, the plug will be
overcooled with the result that insufficiently
burnt carbon will
be
deposited on the insulator
and electrode.
A large amount
of
deposited carbon will prevent
good sparking. Carbon deposits tend
to
get
red-hot themselves, resulting
in
pre-ignition or
knocking. When the
temperature
of the engine
is relatively low,
far example, when
the
motorcycle
is always run in
a t o m or
subjected
to breaking-in without
running
at high speed,
plugs
with
low
heat
range are used. These pIugs
are designed to prevent
heat
dissipation and
are
called hot type plugs.
If these plugs are used
for
high speed running, they may be overheated,
resulting in overheating and pre-ignition oS
the
engine.
The plug gap is adjusted to
0.6 --
0 . 8 m m
(0.024
-
0.031
in.). The gap is correctly
adjusted
using a thickness
gauge
(special tool;
09900-20803). When carbon is deposited on
the spark plug, remove the
carbon with a spark
plug cleaning machine or any tool with a
pointed end. Ifelectrodes are extremely
worn
or
burnt replace the plug. Also repiace the plug if
-
--
-
. .-
:
--
CA UTIO N:
Conjirni rhe
~ h r e a d size
and reach when
replacin
carbon
,
:q
the
plug.
IS
the
reach is too short,
~rqijl be rleposired on the
screw?
portion
o f
r
he plug hole and
engine
will be dams.@.
Fig. 11-9. Normal
carbon Fig. 11-IO. Owrheetin~
condirion
it has
a
broken insulator, damaged thread, etc.
Flg. 11-11.
Wa fouling
o f
Fig. I l - 1 2 . Carbon
stained
pfug
0.6
-
0.8 rnm
(0 024
--
0.03
1
in.)
Fig,
11-7.
11-4