5.
FUEL SYSTEM
FUEL SYSTEM
SERVICE INFORMATION ------------------------------------------ 5-2
TROUBLESHOOTING----------------------------------------------- 5-3
FUEL TANK------------------------------------------------------------ 5-5
FUEL VALVE ---------------------------------------------------------- 5-5
CARBURETOR ------------------------------------------------------ 5-6
5-0
5. FUEL SYSTEM
5-1
5. FUEL SYSTEM
SERVICE INFORMATION
GENERAL INSTRUCTIONS
Gasoline is very dangerous. When working with gasoline, keep sparks and flames away
from the working area.
Gasoline is extremely flammable and is explosive under certain conditions. Be sure to
work in a well-ventilated area.
z Do not bend or twist control cables. Damaged control cables will not operate smoothly.
z When disassembling fuel system parts, note the locations of O-rings. Replace them with new
ones during reassembly.
z Before float chamber disassembly, loosen the drain screw to drain residual gasoline into a
clean container.
z After the carburetor is removed, plug the intake manifold side with a clean shop towel to prevent
foreign matters from entering.
z When cleaning the carburetor air and fuel jets, the O-rings and diaphragm must be removed first
to avoid damage. Then, clean with compressed air.
z When the ATV is not used for over one month, drain the residual gasoline from the float
chamber to avoid erratic idling and clogged slow jet due to deteriorated fuel.
SERVICE DATA
CARBURETOR
Unit：mm (in)
Item Specification
Type BDS42 TYPE
Bore size ∮42
Idle r.p.m 1800±100 rpm
Float height 13 (0.51)
Main jet 162.5
Main air jet 50
Jet needle 6DFY08-54-3
Needle jet 0-6M
Pilot jet 45
Throttle valve 105
By –pass ＃1---0.9 ＃2---0.8 ＃3---0.8
Valve seat 1.5
Starter jet 42.5
Pilot screw STD
Pilot outlet ∮1.1
PV. Stroke 29.6
Throttle cable play 3~5(0.12~0.20)
5-2
5. FUEL SYSTEM
TROUBLESHOOTING
Engine cranks but won’t start Engine lacks power
z No fuel in tank z Clogged air cleaner
z No fuel to carburetor z Faulty carburetor
z Cylinder flooded with fuel z Faulty ignition system
z No spark at plug
z Clogged air cleaner Lean mixture
z Intake air leak z Clogged carburetor fuel jets
z Improper throttle operation z Float level too low
z Intake air leak
Engine idle roughly, stalls or runs poorly z Clogged fuel tank cap breather hole
z Excessively used choke z Kinked or restricted fuel line
z Ignition malfunction
z Faulty carburetor Rich mixture
z Poor quality fuel z Float level too high
z Lean or rich mixture z Clogged air jets
z Incorrect idle speed z Clogged air cleaner
Misfiring during acceleration
z Faulty ignition system
z Faulty carburetor
Backfiring at deceleration
z Float level too low
z Incorrectly adjusted carburetor
z Faulty exhaust muffler
5-3
5. FUEL SYSTEM
CARBURETOR
Complaint Symptom and possible causes Remedy
Trouble with 1. Starter jet is clogged. Clean
starting. 2. Starter pipe is clogged. Clean
3. Air leaking from a joint between starter Check starter body and
body and carburetor. carburetor for tightness,
adjust and replace gasket.
4. Starter plunger is not operating properly. Check and adjust
Idling or low-speed 1. Pilot jet, pilot air jet are clogged or Check and clean.
trouble. loose.
2. Pilot outlet or bypass is clogged. Check and clean.
3. Starter plunger is not fully closed. Check and clean.
Medium or high 1. Main jet or main air jet is clogged. Check and clean.
speed trouble. 2. Needle jet is clogged. Check and clean.
3. Throttle valve is not operating properly. Check throttle valve for
operation.
4. Filter is clogged. Check and clean.
Overflow and fuel 1. Needle valve is worn or damaged. Replace
level fluctuations. 2. Spring in needle valve is broken. Replace
3. Float is not working properly. Check and adjust
4. Foreign matter has adhered to needle Clean
valve.
5. Fuel level is too high or low. Adjust float height.
5-4
5. FUEL SYSTEM
FUEL TANK
Fuel Valve
REMOVAL
Warning
z Keep sparks and flames away from the
work area.
z Wipe off any spilled gasoline.
Remove the seat (See page 2-3), and front
fender.
The fuel valve “OFF” when engine off. Fuel Tube
And fuel valve“ON＂when engine running.
Disconnect the fuel tube from carburetor.
Disconnect the fuel unit connectors.
Remove the four bolts , then remove
the fuel tank.
INSTALLATION
Reverse the “FUEL TANK REMOVAL”
procedures.
Bolts Bolts
FUEL VALVE
REMOVAL
＊ z Keep sparks and flames away from the
work area.
z Drain gasoline into a clean container.
Disconnect all fuel tubes and remove the two
bolts, then remove fuel valve.
Replace the O-rings with new ones if they
are damaged or deteriorated.
Bolts O-ring
5-5
5. FUEL SYSTEM
CARBURETOR
CONSTRUCTION
5-6
5. FUEL SYSTEM
REMOVAL
Disconnect the fuel hose (1).
(1)
Loosen the carburetor clamp screw.
Remove the carburetor side cap (2).
(2)
5-7
5. FUEL SYSTEM
Disconnect the throttle cable (1). Nuts
Remove the O-ring.
(1)
O-ring
DISASSEMBLY
Remove the fuel hose (2) and air vent hoses (3).
(3)
(2)
Remove the throttle stop screw (4).
Remove the choke lever (5). (4)
(5)
5-8
5. FUEL SYSTEM
Remove the carburetor top cap (1).
(1)
＊ Do not use compressed air on the carburetor
body removing the diaphragm：this may
damage the diaphragm.
Remove the spring (2), along with the
diaphragm assembly (3).
(3)
(2)
Remove the jet needle holder (4), spring (5),
E-ring (6), ring (7) and jet needle (8).
(4) (6)
(5)
(7) (8)
5-9
5. FUEL SYSTEM
Remove the diaphragm cover (1).
(1)
Remove the diaphragm (2).
(2)
Remove the float chamber body (3).
(3)
5-10
5. FUEL SYSTEM
Remove the O-ring (1).
(1)
＊Replace the removed O-ring with a new
one to prevent leakage of fuel.
Remove the float pin (2), float (3) and needle
valve (4).
(3)
(2)
(4)
Remove the valve seat (5).
(5)
5-11
5. FUEL SYSTEM
Remove the main jet (1), jet holder (2) and (1),(2)
pilot jet (3).
(3)
remove the pilot air jet (4) counting and
tightening the number of turn. (4)
＊
Before removing the pilot air jet (4), its
setting must be determined. Slowly turn
the pilot screw clockwise and count the
number of turns until it is lightly seated.
Make a note of how many turns were made.
When reassembling the pilot screw, you
will want to set it to its original position.
INSPECTION
Check the following parts for damage and
clogging. Check for stopped wear
Pilot jet Piston valve
Main jet Starter jet
Main air jet Gaskets and O-rings
Pilot air jet Pilot outlet and bypass Foreign substance
Needle jet holder Float
Needle valve Jet needle
Valve seat Diaphragm
Needle valve
If any abnormal condition is found, wash the
part clean.
If damage or clogging is found, replace the
part with a new one.
5-12
5. FUEL SYSTEM
CLEANING
Clean all jets by using compressed air.
After cleaning, reassemble the carburetor
with new seals and gaskets.
＊ Do not use wire to clean the passageways,
valve seat and jets. Used compressed air
only.
FLOAT HEIGHT ADJUSTMENT
To check the float height, turn the carburetor
upside down. Measure the float height (A) (A) 13mm
while the float arm is just contacting the
needle valve using a vernier calipers.
Bend the float arm (1) as necessary to bring
the height to the specified level.
After adjustment, check the float height and
the fuel level again.
(1)
5-13
5. FUEL SYSTEM
REASSEMBLY
Carburetor reassembly can be performed in
the reverse order of disassembly. (1)
When reassembling, carefully observe the
following instructions.
After cleaning, reinstall the pilot air jet (1) to
the original setting by turning the screw in until
it lightly seat, and then backing it out the same
number of turns counted during disassembly.
Install the pilot jet (2), jet holder (3) and
main jet (4).
(3),(4)
(2)
Align the hole (5) of the diaphragm with
passageway on the carburetor body.
＊ When installing the diaphragm, make sure
the diaphragm is seated at the concave
section of the carburetor. (5)
5-14
5. FUEL SYSTEM
Apply SUPER GREASE to thread part of the
throttle stop screw, then install the throttle
stop screw to the carburetor.
REMOUNTING
Remount the carburetor assembly in the reverse
order of removal.
Pay attention to the following points：
Align the lug on the carburetor with intake
pipe’s cutout.
Connect the carburetor hoses properly.
After the carburetor assembly has been
remounted onto the engine, perform the
following adjustment.
Throttle cable adjustment. -----------Refer to page 3-3
Idle speed adjustment. -----------Refer to page 3-10
5-15
