Kymco MO FILLY 50LX Service Manual - chap 05 (alimentazione)
5. FUEL SYSTEM
5-0
FILLY LX 50
5
5
5. FUEL SYSTEM
5-1
FILLY LX 50
Fuse
12V Battery
Regulator
/Rectifier
L/Y
W
Auto Bystarter
Ignition Switch
BGY
Y
Lighting
System
5W
5W
G/B
M
5. FUEL SYSTEM
5-2
FILLY LX 50
FUEL PUMP
CONSTRUCTION:
The fuel pump adopted for this model is a vacuum-type fuel pump which utilizes the positive and
negative pulsating pressures produced by the engine crankcase to control the oil pump diaphragms
and deliver fuel from the fuel tank to the carburetor through the suction valve and outlet valve.
FUEL PUMP CONSTRUCTION
Diaphragms
Inlet
Outlet
Suction Valve
Outlet Valve
Pulsating Pressure
from Crankcase
5. FUEL SYSTEM
5-3
FILLY LX 50
SERVICE INFORMATION
GENERAL INSTRUCTIONS
• When disassembling the carburetor, be sure to service the vacuum piston and float chamber.
• Do not bend or twist control cables. Damaged control cables will not operate smoothly.
• When disassembling fuel system parts, note the locations of O-rings. Replace them with new
ones during assembly.
• Before float chamber disassembly, loosen the drain screw to drain the residual gasoline into a
clean container.
• After the carburetor is removed, plug the intake manifold side with a clean shop towel to prevent
foreign matters from entering.
• Remove the vacuum diaphragm before cleaning the carburetor air and fuel passages with
compressed air to avoid damaging the vacuum diaphragm.
• When the motorcycle 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.
SPECIFICATIONS
Item
Standard
Venturi dia. (mm)
20
Type
CVK
Float level (mm)
17
Main jet
#85
Slow jet
#35
Idle speed
1900rpm
Throttle grip free play
2_ 6mm
Pilot screw opening
2±
1
/2
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.
SERVICE INFORMATION
......................
5-3 ACCELERATING PUMP
......................
5-11
TROUBLESHOOTING
.............................
5-4 CARBURETOR INSTALLATION
........
5-12
CARBURETOR REMOVAL
....................
5-5 PILOT SCREW ADJUSTMENT
............
5-13
AUTO BYSTARTER
.................................
5-5 FUEL TANK
...........................................
5-14
AIR CUT-OFF VALVE
.............................
5-7 AUTO FUEL VALVE
.............................
5-15
VACUUM CHAMBER
.............................
5-7 FUEL UNIT
.............................................
5-18
FLOAT CHAMBER
..................................
5-9 AIR CLEANER
........................................
5-18
5. FUEL SYSTEM
5-4
FILLY LX 50
TROUBLESHOOTING
Engine is hard to start Misfiring during acceleration
• No spark at plug (!Section 15) • Faulty ignition system
• Compression too low • Lean mixture
• No fuel to carburetor • Faulty accelerating pump
-Clogged fuel filter Engine idles roughly, stalls or runs poorly
-Restricted fuel line • Clogged fuel system
-Faulty float valve • Ignition malfunction
-Incorrectly adjusted float level • Rich or lean mixture
• Engine flooded with fuel • Contaminated fuel
-Clogged air cleaner • Intake air leak
-Fuel overflowing • Incorrect idle speed
• Intake air leak • Incorrectly adjusted pilot screw
• Contaminated fuel • Clogged idle system or auto bystarter passages
• Faulty auto bystarter • Incorrectly adjusted float level
• Clogged idle system or auto bystarter passages Lean mixture
Rich mixture • Clogged fuel jets
• Faulty auto bystarter • Faulty float valve
• Faulty float valve • Float level too low
• Float level too high • Clogged fuel system
• Clogged air jets • Intake air leak
• Dirty air cleaner • Improper vacuum piston operation
• Flooded carburetor • Improper throttle operation
Backfiring at deceleration
• Lean mixture in idle system
• Improper air cut-off valve operation
5. FUEL SYSTEM
5-5
FILLY LX 50
CARBURETOR REMOVAL
Remove the frame right side cover. (!2-4)
Disconnect the auto bystarter wire
connector.
Remove the met-in box. (!2-3)
Loosen the drain screw and drain the fuel
from the float chamber.
Disconnect the fuel tube and vacuum tube at
the carburetor.
Loosen the throttle cable adjusting nut and
lock nut, and disconnect the throttle cable
from the carburetor.
Loosen the carburetor intake manifold band
and air cleaner connecting tube band screws
and then remove the carburetor.
AUTO BYSTARTER
OPERATION INSPECTION
Measure the resistance between the auto
bystarter wire terminals.
Resistance: 10W max. (10 minutes
minimum after stopping the engine)
If the reading is not within the limit, replace
the auto bystarter with a new one.
Adjusting Nut
Fuel Tube
Intake Manifold
Band
Air Cleaner Connect ing
T ube Band
Throttle Cable
Lock Nut
Auto Bystarter Wire
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