Suzuki GS-1000 Service Manual page 99

FUEL SYSTEM
rV
CARBURETORS
DO NOT ADJUST THE AIR SCREW A N D
PILOT SCREW. Both of
these components are
pre-set at the factory using very specialized
equipment. They can not he reset to the
exact
setting determined by the factory. Refer
to
the
emission control systems and regulation chapter
for further information.
Description
This motorcycle has four carburetors,
each of
which must be
so
adjusted properly
to
assure
engine performance.
The link motion is moved by
the
two throttle
cables that
are
connected to the throttle grip to
open or close all carburetor throttle valves at
the
same time.
1.
k t
ncedle
2.
Veedle pt
*-
T 4 ,
-@
?
Float
-
-
-
-
-
-
-9
1 M a n p r
5 V d l e
valve
-
6 Throt~le valve
Fig. 8-3.
Each carburetor has four
units
for regulating
and supplying fuel. There i s the staner unit for
supplying a rich fuel-air
mixture
when starting
the engine, a pilot unit
for supplying
fuel when
the engine is idling, a main unit for supplying
fuel when the engine is running at medium-or
high-sped, and a float unit for maintaining
a
constant carburetor fuel
level.
The carburetors
mix gasoline with
air,
and regulates the mixture.
Carburetor malfunctioning or trouble generally
occurs due to a bad mixing ratio, which is the
result
of
wearing,
blocking by Foreign matter. or
an improper fuel level. The following are some
of the symptoms of a faulty
carburetor.
Fuel-air mixtare
too
lean
1.
The engine becomes overheated.
2. The engine runs well when the starter is
opened further.
3.
Poor acceleration.
4.
The spark plugs &come overheated.
5. Engine speed is irregular.
6. Exhaust gas is
light.
Fuel-air m b e
too
rich
1.
The engine is sluggish, and does
not
run
smoothly.
2. The engine runs badly when the starter
is
opened further.
3. The engine runs badly after being warmed
UP.
4.
The engine runs well when the air filter is
removed.
5. The
spark
plugs get soiled
with
carbon.
6. Exhaust gas is
blackish in
color.
STARTER UNI"
The starter unit
is a starting aid device which
supplies
a
highly concentrated gasoline-air
mixture to
a
cold engine at initial starting.
Jt
consists
of
a
starter
jet
0,
starter pipe
0,
and
starter plunger
@.
Refer to
close
the throttle
valve, open the starter plunger fully, and switch
on the
starter, or kick. Then the engine
will
generate negative pressure to draw the fuel
through the fuel injection ports.
?'he
fuel is metered by the starter jet,
is mixed
with the air coming from the float chamber in
the
starter pipe, sucked into the starter plunger
chamber,
where
it is
mixed with the starter's
primary air. and then drawn out
into the main
bores from t h e injection ports a s a
well-atomized and concentrated fuel very
suitable for starting purposes. This fuel-air
mixture is added to the fuel-air mixture being
supplied by the pilot circuit in
the carburetors.
When
using
the starter. the throttle valve must
be completely closed. If the throttle valve is
opened. the negative pressure falls and will not
build up at injection ports and rhe engine will
not
be able to draw s u ~ c i e n t fuel. The starter
plunger
has
a needle-like tip. which closes the
starter unit's fuel passage. If the starter lever is
not pulled all the
way
up.
the
fuel passage will
not open
to
let the gasoline
flow.
If the starter
pipe's bleed hole is clogged, the fuel will
not
be atomized properly.
8- 3