FUEL SYSTEM/CARBURETOR/ FUEL PUMP/ FUEL …kymcoman.free.fr/revue technique/GD125_150 cap 13 (alimentazione).pdf · auto bystarter installation----- 13-14 float chamber assembly

13. FUEL SYSTEM/CARBURETOR/FUEL PUMP/ FUEL TANK

13-0

GRAND DINK 125/150

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FUEL SYSTEM/CARBURETOR/FUEL PUMP__________________________________________________________________________________

FUEL SYSTEM --------------------------------------------------------- 13- 1SCHEMATIC DRAWING ---------------------------------------------- 13- 2OPERATION OF CARBURETOR JETS------------------------------ 13- 3SERVICE INFORMATION -------------------------------------------- 13- 5CARBURETOR REMOVAL ------------------------------------------- 13- 7VACUUM CHAMBER DISASSEMBLY------------------------------ 13- 7FLOAT CHAMBER DISASSEMBLY--------------------------------- 13- 9AUTO BYSTARTER INSPECTION/REMOVAL-------------------- 13-11AIR CUT-OFF VALVE (A.C.V.)-------------------------------------- 13-12AUTO BYSTARTER INSTALLATION ------------------------------ 13-14FLOAT CHAMBER ASSEMBLY ------------------------------------- 13-15FLOAT LEVEL INSPECTION ---------------------------------------- 13-16VACUUM CHAMBER ASSEMBLY ---------------------------------- 13-16CARBURETOR INSTALLATION ------------------------------------ 13-17FUEL PUMP REMOVAL/DISASSEMBLY -------------------------- 13-18FUEL PUMP INSPECTION-------------------------------------------- 13-19FUEL PUMP ASSEMBLY --------------------------------------------- 13-19FUEL PUMP INSTALLATION --------------------------------------- 13-20FUEL TANK REMOVAL ---------------------------------------------- 13-20

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13-1

GRAND DINK 125/150

FUEL SYSTEM


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GRAND DINK 125/150

SCHEMATIC DRAWING


13-3

GRAND DINK 125/150

OPERATION OF CARBURETOR JETS1. LOW SPEED

Venturi (slightly opened throttle valve)Low Speed Air Inlet

※ Fuel in Float Chamber‡ Slow Jet-------------------- Low Speed Small Jet Holes

2.MIDDLE SPEEDVenturi (halfway opened throttle valve)High Speed Air Jet

※ Fuel in Float Chamber‡ Main JetMain Jet (The slow jet also works.)

Low & Middle Speed Supplementary Device:

Vacuum Tube Low Speed Air Jet

Main Jet

Vacuum Diaphragm

Throttle

Valve

Low & Middle Speed Supplementary Fuel Inlets

Slow JetBypass Jet

Pilot Screw

ACV

Air

※ Air

※ Air

Air Bleed Holes‡ Mixture…….

Air Bleed Holes‡ Mixture…….


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GRAND DINK 125/150

FUEL PUMP

CONSTRUCTION:The fuel pump adopted for this model is a vacuum-type fuel pump which utilizes the positive andnegative pulsating pressures produced by the engine crankcase to control the oil pump diaphragmsand 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 Pressurefrom Crankcase


13-5

GRAND DINK 125/150

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 duringassembly.

• 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 thediaphragms.

• All cables, fuel lines and wires must be routed and secured at correct locations.

• When removing the fuel tank, keep sparks and flames away from the working area.

• When removing the fuel tank, the remaining fuel in the tank must be lower than _ of the fuel tankcapacity to avoid gasoline overflowing.

• Fuel tank capacity: 10.5 liters

SPECIFICATIONS

125cc

VE0222 B

18.5

2_ ±_

150cc

35#

1500±100rpm

40cc/1500rpm/10

seconds

Venturi dia. (mm) VE26 VE26

Identification number VE060A VE061A

Float level (mm) 18.5 18.5

Pilot screw opening 2±1/2 2 1/2±1/2

Main jet 102# 102#

Slow jet 35# 35#

Idle speed 1700 1700

Fuel pump output 17L/Hr/7000rpm 17L/Hr/7000rpm

SPECIAL TOOLS

Float level gauge

Fuel unit remover


13-6

GRAND DINK 125/150

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

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 highLean 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

Engine is hard to start• No fuel in tank• Restricted fuel line• Clogged fuel strainer• Faulty fuel pump• Broken or clogged vacuum tube• Faulty or clogged charcoal canister

Lean mixture• Clogged charcoal canister• Bent, kinked or restricted fuel line• Clogged fuel strainer• Float level too low


13-7

GRAND DINK 125/150

CARBURETOR REMOVALRemove the seat, met-in box and centercover.Disconnect the fuel tube and vacuum tube atthe carburetor.Disconnect the auto bystarter wire.

Loosen the throttle cable adjusting nut andlock nut, and disconnect the throttle cablefrom the carburetor.Loosen the air cleaner connecting tube bandand carburetor intake manifold band and thenremove the carburetor.

VACUUM CHAMBERDISASSEMBLYLoosen the drain screw and drain the fuelfrom the float chamber.

Auto Bystarter Wire Auto Bystarter

Fuel Tube

Intake Manifold Band

Air Cleaner Connecting TubeBand

Drain Screw


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GRAND DINK 125/150

Remove the two vacuum chamber coverscrews and the cover.

Remove the compression spring and vacuumpiston.

Remove the needle holder, spring and jetneedle from the piston.

VACUUM PISTON INSPECTIONInspect the vacuum piston and jet needle forwear or damage.Inspect the diaphragm for deterioration andtears.

Vacuum Chamber Cover

Diaphragm

Screws

Spring

Spring

• Be careful not to damage the vacuumpiston diaphragm.

＊

Vacuum Piston

Vacuum Piston

Needle HolderJet Needle


13-9

GRAND DINK 125/150

FLOAT CHAMBER DISASSEMBLYRemove the four float chamber screws andthe float chamber.

Remove the float pin, float and float valve.

FLOAT VALVE INSPECTIONInspect the float valve seat contact area forwear.

Float Chamber

Float Valve

Float

Float Pin

Float Valve Seat

Screws

Float Valve


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GRAND DINK 125/150

JETS/SCREWS REMOVAL

Remove the main jet, needle jet holder andneedle jet.Remove the slow jet.

Clean the removed the main jet, needle jetholder, needle jet and slow jet with detergentoil.

Pilot Screw (P.S.)

Pilot Screw

Slow Jet

• Be sure to use clean detergent oil.＊

Main Jet

Needle Jet Holder

Needle Jet

• Before removing the pilot screw, turnthe pilot screw clockwise until it seatslightly and record the rotating turns.Do not force the pilot screw against itsseat to avoid seat damage.

＊

Slow Jet

Main Jet


13-11

GRAND DINK 125/150

AUTO BYSTARTER INSPECTION/REMOVALAUTO BYSTARTER INSPECTIONMeasure the resistance between the autobystarter wire terminals.Resistance: 10W (10 minutes minimumafter stopping the engine)If the reading is not within the limit, replacethe auto bystarter with a new one.

Connect a hose to the fuel enriching circuitof the carburetor. Connect the autobystarter yellow wire to the positive (+)terminal of a battery and green wire to thenegative (-) terminal. Wait 5 minutes andblow the hose with mouth. If the passage isblocked, the auto bystarter is normal.Disconnect the auto bystarter from thebattery. Wait 30 minutes and blow the hosewith mouth.. If air can be blown into thehose, the auto bystarter is normal.

AUTO BYSTARTER REMOVALRemove the two set plate screws and setplate and then remove the auto bystarterfrom the carburetor body.

Auto Bystarter

Hose

Yellow

Screws

Set Plate

Green


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GRAND DINK 125/150

AUTO BYSTARTER INSPECTIONCheck the auto bystarter valve and needlefor nicks, wear or damage.If any faulty part is found, replace the autobystarter with a new one.

AIR CUT-OFF VALVE (A.C.V.)A.C.V. REMOVALRemove the two screws and the air cut-offvalve cover.

Remove the spring, diaphragm and O-rings.Inspect the diaphragm and spring for wear ordamage.

Bystarter Needle

Air Cut-off Valve Cover

Bystarter Valve

Spring

Screws

Cover

Diaphragm


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GRAND DINK 125/150

Disconnect the hose at the valve seat.Remove the two screws and the air cut-offvalve body.

CARBURETOR BODY CLEANINGBlow compressed air through all passages ofthe carburetor body.

A.C.V. ASSEMBLYInstall the O-ring onto the air-cut-off valvebody and then install the valve body to thecarburetor 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 facetoward the valve body side.

＊

Air Cut-off Valve Body

Screws


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GRAND DINK 125/150

Install the O-ring onto the air-cut-off valvebody securely.

Install the diaphragm, spring, and cover.

Install and tighten the two screws attachingthe air cut-off valve cover.Connect the hose.

AUTO BYSTARTER INSTALLATIONInstall the auto bystarter and set plate.Install and tighten the two screws.

Auto Bystarter

Screws

• Install the O-ring with the flat facetoward the valve body side.

＊

SpringCover

Diaphragm O-ring

Screws

Set Plate

• Insert the auto bystarter into thecarburetor body until it bottoms andposition the set plate into the uppergroove in the bystarter.

• Install the set plate with its round facefacing down.

＊


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GRAND DINK 125/150

FLOAT CHAMBER ASSEMBLYInstall 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

Slow Jet Main Jet

• Be sure to record the rotating turnswhen it is removed.

＊


13-16

GRAND DINK 125/150

FLOAT LEVEL INSPECTIONMeasure the float level at the location of themain jet (just contacting the float valve).Float Level: 18.5±1.0mmReplace the float if the level is incorrect.Check the operation of the float and thenreinstall the float chamber.

VACUUM CHAMBER ASSEMBLYFirst install the jet needle and spring into thevacuum chamber and then install the needleholder.

Install the vacuum piston into the carburetorbody.

Install the spring.Install the vacuum chamber cover and tightenit with the two screws.

Diaphragm

Float

• Be careful not to let the diaphragm slip.• If the diaphragm cannot be positioned

correctly because of expansion, dry thediaphragm before installation.

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Spring

Spring

Vacuum Piston

Vacuum Piston

Needle HolderJet Needle

• Align the hole in the diaphragm withthe hole in the carburetor body.

＊


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GRAND DINK 125/150

Check the heater with battery.If the heater is getting hot, means the heaterwithout problem, otherwise the heater has tobe changed.

CARBURETOR INSTALLATIONTighten the drain screw.Install the carburetor onto the intakemanifold and tighten the band.Install the air cleaner connecting tube andtighten the band.Connect the throttle cable to the carburetor.

Connect the auto bystarter wire.Connect the fuel tube and vacuum tube tothe carburetor.Perform the following inspections andadjustments:•Throttle grip free play (!3-3)•Idle speed (!3-6)Install the seat, met-in box and frame centercover.

Auto Bystarter Wire

Fuel Tube

Intake Manifold Band Air Cleaner ConnectingTube Band

Heater

• After connecting the throttle cable,adjust the throttle grip free play to2_ 6mm.

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Throttle Cable


13-18

GRAND DINK 125/150

FUEL PUMP REMOVALRemove the frame center cover.Disconnect the fuel pump inlet, outlet andvacuum tubes.Remove the two fuel pump attaching boltsand the fuel pump.

FUEL PUMP DISASSEMBLYRemove the four fuel pump body screws.

Disassemble the fuel pump.

Inlet Screws

Fuel Strainer

Outlet Tube

Vacuum Tube Inlet Tube

Vacuum Tube Outlet


13-19

GRAND DINK 125/150

FUEL PUMP INSPECTIONInspect the fuel pump diaphragms A and Bfor damage.Inspect each gasket for damage.

Inspect the suction valve, outlet valve andrelief valve in the fuel pump body fordamage, cracks or foreign matters.

FUEL PUMP ASSEMBLYAssemble the fuel pump in the reverse orderof disassembly.

Inlet Spring

Suction Valve

Diaphragm

Outlet Valve

Gaskets

Relief ValveOutlet

Dowel Pins

Dowel Pin HolesFuel Pump Body

• During assembly, be sure to install thegaskets and diaphragms properly toavoid damage.

• Do not allow any foreign matter toenter the fuel pump during assembly.

＊

Spring


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GRAND DINK 125/150

FUEL PUMP INSTALLATIONInstall the fuel pump and secure it with thetwo bolts.Connect the fuel pump inlet, outlet andvacuum tubes.Install the seat, met-in box and frame centercover.

Measure the fuel pump output.Start the engine and disconnect the fueloutlet tube and place a clean container underthe tube to check the fuel output.Output: 40cc/1500rpm/10 seconds .

FUEL TANK REMOVALRemove the floor board. (!2-4)Remove the leg shield . (!2-5)Disconnect the fuel unit wire connector.Remove the fuel tube between the fuel tankand the fuel filler.Disconnect the fuel vapor tube.Remove the fuel tank.The installation sequence is the reverse ofremoval.

Container

Fuel Pump

Fuel Pump Outlet Tube

Fuel Strainer

Outlet Tube Vacuum Tube Inlet Tube

Fuel Unit Fuel Vapor Tube

Fuel Strainer Tube to Fuel Filler


13-21

GRAND DINK 125/150

FUEL STRAINER REMOVALRemove the fuel strainer from the fuel tank.INSPECTIONInspect if the fuel strainer is clogged andclean it with compressed air.Replace the fuel strainer at every 6000 km.

INSTALLATIONInstall the fuel strainer with its arrow marktoward the fuel pump.

• When removing the fuel strainer, do notallow flames or sparks near theworking area and drain the residualgasoline into a container.

＊

Fuel Strainer

Documents

FUEL SYSTEM/CARBURETOR/ FUEL PUMP/ FUEL …kymcoman.free.fr/revue technique/GD125_150 cap 13 (alimentazione).pdf · auto bystarter installation----- 13-14 float chamber assembly