Kymco MO D200 Service Manual - chap 13 (alimentazione)

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13. FUEL SYSTEM/CARBURETOR/FUEL PUMP
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SCHEMATIC DRAWING ---------------------------------------------- 13- 1 SERVICE INFORMATION -------------------------------------------- 13- 4 TROUBLESHOOTING ------------------------------------------------- 13- 4 CARBURETOR REMOVAL ------------------------------------------- 13- 6 VACUUM CHAMBER DISASSEMBLY------------------------------ 13- 6 FLOAT CHAMBER DISASSEMBLY--------------------------------- 13- 8 AUTO BYSTARTER INSPECTION/REMOVAL-------------------- 13-10 AIR CUT-OFF VALVE (A.C.V.)-------------------------------------- 13-11 AUTO BYSTARTER INSTALLATION ------------------------------ 13-13 FLOAT CHAMBER ASSEMBLY ------------------------------------- 13-14 FLOAT LEVEL INSPECTION ---------------------------------------- 13-15 VACUUM CHAMBER ASSEMBLY ---------------------------------- 13-15 CARBURETOR INSTALLATION ------------------------------------ 13-16 FUEL PUMP REMOVAL/DISASSEMBLY -------------------------- 13-17 FUEL PUMP INSPECTION-------------------------------------------- 13-18 FUEL PUMP ASSEMBLY --------------------------------------------- 13-18 FUEL PUMP INSTALLATION --------------------------------------- 13-19
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FUEL SYSTEM
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SCHEMATIC DRAWING
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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
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SERVICE INFORMATION
GENERAL INSTRUCTIONS
When working with gasoline, keep away from sparks and flames.
Note the locations of O-rings when disassembling and replace them with new ones during
assembly.
Before float chamber disassembly, drain the residual gasoline from the float chamber.
Do not try to disassemble the auto bystarter.
When assembling the vacuum chamber and air cut-off valve, be careful not to damage the
diaphragms.
All cables, fuel lines and wires must be routed and secured at correct locations.
SPECIFICATIONS
Venturi dia. (mm)
VE26
Identification number
VE090
Float level (mm)
18.5
Pilot screw opening
2±_
Main jet
102#
Slow jet
35#
Idle speed
1600±100rpm
Fuel pump output
40cc/1600rpm/10 seconds
SPECIAL TOOLS
Float level gauge Fuel unit remover
TROUBLESHOOTING
Engine does not start Engine idles roughly, stalls or runs poorly
No fuel in tank Incorrect idle speed
Restricted fuel line Rich mixture
Too much fuel getting to cylinder Lean mixture
Clogged air cleaner Clogged air cleaner
Contaminated fuel Intake air leak
Faulty fuel pump Contaminated fuel
Faulty air-cut off valve
Damaged vacuum tube and connectors
Damaged carburetor insulator
B
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Throttle does not open fully, so engine stalls Rich mixture
Damaged vacuum piston diaphragm Auto bystarter valve opens excessively
Clogged diaphragm hole Faulty float valve
Float level too high
Lean mixture Clogged air jets
Clogged fuel jets Auto bystarter valve set plate installed in
Clogged fuel tank cap breather hole
the wrong groove
Clogged fuel filter Clogged air cleaner
Bent, kinked or restricted fuel line
Faulty float valve
Float level too low
Faulty fuel pump or insufficient output
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CARBURETOR REMOVAL
Remove the seat, met-in box and center cover. Disconnect the fuel tube and vacuum tube at the carburetor. Disconnect the auto bystarter wire.
Loosen the throttle cable adjusting nut and lock nut, and disconnect the throttle cable from the carburetor. Loosen the air cleaner connecting tube band and carburetor intake manifold band and then remove the carburetor.
VACUUM CHAMBER DISASSEMBLY
Loosen the drain screw and drain the fuel from the float chamber.
Auto Bystarter Wire
Auto Bystarter
Fuel Tube
Intake Manifold Band
Air Cleaner Connecting Tube Band Drain Screw
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Remove the two vacuum chamber cover screws and the cover.
Remove the compression spring and vacuum piston.
Remove the needle holder, spring and jet needle from the piston.
VACUUM PISTON INSPECTION
Inspect the vacuum piston and jet needle for wear or damage. Inspect the diaphragm for deterioration and tears.
Vacuum Chamber Cover
Diaphragm
Screws
Spring
Spring
Be careful not to damage the vacuum
piston diaphragm.
Vacuum Piston
Vacuum Piston
Needle Holder
Jet Needle
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FLOAT CHAMBER DISASSEMBLY
Remove the four float chamber screws and the float chamber.
Remove the float pin, float and float valve.
FLOAT VALVE INSPECTION
Inspect the float valve seat contact area for wear.
Float Chamber
Float Valve
Float
Float Pin
Float Valve Seat
Screws Float Valve
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JETS/SCREWS REMOVAL
Remove the main jet, needle jet holder and needle jet. Remove the slow jet.
Clean the removed the main jet, needle jet holder, needle jet and slow jet with detergent oil.
Pilot Screw (P.S.)
Pilot Screw
Slow Jet
Be sure to use clean detergent oil.
Main Jet
Needle Jet Holder
Before removing the pilot screw, turn
the pilot screw clockwise until it seats lightly and record the rotating turns. Do not force the pilot screw against its seat to avoid seat damage.
Needle Jet Holder
Slow Jet
Main Jet
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AUTO BYSTARTER INSPECTION /REMOVAL
AUTO BYSTARTER INSPECTION
Measure the resistance between the auto bystarter wire terminals.
Resistance: 10Ω (10 minutes minimum after stopping the engine)
If the reading is not within the limit, replace the auto bystarter with a new one.
Connect a hose to the fuel enriching circuit of the carburetor. Connect the auto bystarter yellow wire to the positive (+) terminal of a battery and green wire to the negative (-) terminal. Wait 5 minutes and blow the hose with mouth. If the passage is blocked, the auto bystarter is normal. Disconnect the auto bystarter from the battery. Wait 30 minutes and blow the hose with mouth.. If air can be blown into the hose, the auto bystarter is normal.
AUTO BYSTARTER REMOVAL
Remove the two set plate screws and set plate and then remove the auto bystarter from the carburetor body.
Auto Bystarter
Screws
Set Plate
Hose
Yellow Green
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AUTO BYSTARTER INSPECTION
Check the auto bystarter valve and needle for nicks, wear or damage. If any faulty part is found, replace the auto bystarter with a new one.
AIR CUT-OFF VALVE (A.C.V.)
A.C.V. REMOVAL
Remove the two screws and the air cut-off valve cover.
Remove the spring, diaphragm and O-rings. Inspect the diaphragm and spring for wear or damage.
Bystarter Needle
Air Cut-off Valve Cover
Bystarter Valve
Spring
Screws
Cover
Diaphragm
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Disconnect the hose at the valve seat. Remove the two screws and the air cut-off valve body.
CARBURETOR BODY CLEANING
Blow compressed air through all passages of the carburetor body.
A.C.V. ASSEMBLY
Install the O-ring onto the air-cut-off valve body and then install the valve body to the carburetor with the two screws.
Hose
O-ring
Air Cut-off Valve Body
Make sure that no fuel jet is clogged.
Install the O-ring with the flat face
toward the valve body side.
Air Cut-off Valve Body
Screws
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Install the O-ring onto the air-cut-off valve body securely.
Install the diaphragm, spring, and cover.
Install and tighten the two screws attaching the air cut-off valve cover. Connect the hose.
AUTO BYSTARTER INSTALLATION
Install the auto bystarter and set plate. Install and tighten the two screws.
Auto Bystarter
Screws
Install the O-ring with the flat face
toward the valve body side.
Spring
Cover
Diaphragm
O-ring
Screws
Set Plate
Insert the auto bystarter into the
carburetor body until it bottoms and position the set plate into the upper groove in the bystarter.
Install the set plate with its round face
facing down.
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FLOAT CHAMBER ASSEMBLY
Install the needle jet and needle jet holder. Install the main jet. Install the slow jet.
Install the pilot screw.
Install the float valve, float and float pin.
Float Valve
Float
Float Pin
Pilot Screw
Needle Jet Holder
Slow Jet Holder
Main Jet Holder
Be sure to record the rotating turns
when it is removed.
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FLOAT LEVEL INSPECTION
Measure the float level at the location of the main jet (just contacting the float valve).
Float Level: 18.5±1.0mm Replace the float if the level is incorrect.
Check the operation of the float and then reinstall the float chamber.
VACUUM CHAMBER ASSEMBLY
First install the jet needle and spring into the vacuum chamber and then install the needle holder.
Install the vacuum piston into the carburetor body.
Install the spring.
Diaphragm
Float
Spring
Vacuum Piston
Align the hole in the diaphragm with
the vacuum passage in the carburetor body.
Diaphragm
Spring
Vacuum Piston
Needle Holder
Jet Needle
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Install the vacuum chamber cover and tighten it with the two screws.
CARBURETOR INSTALLATION
Tighten the drain screw. Install the carburetor onto the intake manifold and tighten the band. Install the air cleaner connecting tube and tighten the band. Connect the throttle cable to the carburetor.
Connect the auto bystarter wire. Connect the fuel tube and vacuum tube to the carburetor. Perform the following inspections and adjustments:
Throttle grip free play (3-3)
Idle speed (3-6)
Install the seat, met-in box and frame center cover.
Auto Bystarter Wire
Be careful not to let the diaphragm slip.
If the diaphragm cannot be positioned
correctly because of expansion, dry the diaphragm before installation.
Vacuum Chamber Cover
Fuel Tube
Intake Manifold Band
Air Cleaner Connecting Tube Band
Screws
After connecting the throttle cable,
adjust the throttle grip free play to 2_ 6mm.
Throttle Cable
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FUEL PUMP REMOVAL
Remove the frame center cover. Disconnect the fuel pump inlet, outlet and vacuum tubes.
Remove the fuel pump attaching two bolts and the fuel pump.
FUEL PUMP INSTALLATION
Install the fuel pump and secure it with the two bolts. Connect the fuel pump inlet, outlet and vacuum tubes. Install the seat, met-in box and frame center cover.
Measure the fuel pump output. Start the engine and disconnect the fuel outlet tube and place a clean container under the tube to check the fuel output.
Output: 40cc/1500rpm/10 seconds .
Container
Fuel Pump
Fuel Pump
Outlet Tube
Fuel Strainer
Outlet Tube
Vacuum Tube
Inlet Tube
Outlet Tube
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FUEL STRAINER REMOVAL
Remove the fuel strainer from the inlet tube.
INSPECTION
Inspect if the fuel strainer is clogged and clean it with compressed air.
INSTALLATION
Install the fuel strainer with its arrow mark toward the fuel pump.
When removing the fuel strainer, do not
allow flames or sparks near the working area and drain the residual gasoline into a container.
Fuel Strainer
Arrow Mark
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