5. FUEL SYSTEM

5-0

AGILITY CITY 125

5

5

5. FUEL SYSTEM

5-1

AGILITY CITY 125

Fuse

12V Battery

Regulator /Rectifier

L/Y

W

Auto Bystarter

Ignition SwitchC

DI U

nit

B

G

Y

Y

LightingSystem

Resistor

5Ω5W

G/B

M

5. FUEL SYSTEM

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AGILITY CITY 125

SERVICE INFORMATIONGENERAL 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) φ26Type VEFloat level (mm) 17Main jet #104Slow jet #35Idle speed 1700rpm±100Throttle grip free play 2～6mmPilot screw opening 3±1/2

Gasoline is very dangerous. When working with gasoline, keep sparks and flames awayfrom the working area.Gasoline is extremely flammable and is explosive under certain conditions. Be sure towork in a well-ventilated area.

SERVICE INFORMATION.......................5-2 CARBURETOR INSTALLATION.........5-10

TROUBLESHOOTING..............................5-3 PILOT SCREW ADJUSTMENT ............5-11

CARBURETOR REMOVAL.....................5-4 FUEL TANK............................................5-12

AUTO BYSTARTER .................................5-4 FUEL UNIT .............................................5-13

AIR CUT-OFF VALVE .............................5-6 AIR CLEANER .......................................5-13

VACUUM CHAMBER..............................5-6

FLOAT CHAMBER...................................5-8

5. FUEL SYSTEM

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AGILITY CITY 125

TROUBLESHOOTINGEngine 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 mixtureRich 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 operationBackfiring at deceleration• Lean mixture in idle system• Improper air cut-off valve operation

5. FUEL SYSTEM

5-4

AGILITY CITY 125

CARBURETOR REMOVALRemove the frame right side cover. ( 2-4)Disconnect the auto bystarter wireconnector.Remove the met-in box. ( 2-3)

Loosen the drain screw and drain the fuelfrom the float chamber.Disconnect the fuel tube and vacuum tube atthe carburetor.Disconnect the TPS coupler and remove theTPS unit

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

AUTO BYSTARTEROPERATION INSPECTIONMeasure the resistance between the autobystarter wire terminals.Resistance: 10Ω max. (10 minutesminimum after stopping the engine)If the reading is not within the limit, replacethe auto bystarter with a new one.

Adjusting Nut

Fuel Tube

Intake Manifold Band

Air Cleaner ConnectingTube Band

Throttle Cable Lock Nut

Auto Bystarter Wire

Auto Bystarter

Vacuum Tube

TPS Unit

5. FUEL SYSTEM

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AGILITY CITY 125

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 or vacuumpump. If the passage is blocked, theauto bystarter is normal.Disconnect the auto bystarter from thebattery. Wait 30 minutes and blow the hosewith mouth or vacuum pump. If air can beblown into the hose, the auto bystarter isnormal.

REMOVALRemove the set plate screws and set plate.Remove the auto bystarter from thecarburetor.

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

INSTALLATIONInsert the auto bystarter into the carburetorbody until it bottoms.Position the set plate into the groove in theauto bystarter and tighten the screws.

Auto Bystarter

Screws

Bystarter Needle

Bystarter Valve

Auto Bystarter

Screws

Set Plate

Vacuum Pump

Adopter

Set Plate

• Be sure to install the auto bystarter andset plate properly.

• Install the set plate with its bottom facefacing down.

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5. FUEL SYSTEM

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AGILITY CITY 125

AIR CUT-OFF VALVEDISASSEMBLYRemove the two screws attaching the aircut-off valve.Remove the spring and vacuum diaphragm.Check the vacuum diaphragm for cracks ordamage and check each passage forclogging.

ASSEMBLYInstall the vacuum diaphragm onto thecarburetor.Install the spring and air cut-off valve cover.Install the throttle cable set plate and tightenthe two screws.

VACUUM CHAMBERDISASSEMBLYRemove the two vacuum chamber coverscrews and the cover.

Remove the spring and vacuum diaphragm/piston.

Spring

Vacuum Diaphragm/Piston

Air Cut-off Valve Cover

CoverScrews

Screws

• Be sure to set the vacuum diaphragmlip into the groove on the carburetor.

• When installing the air cut-off valvecover, make sure that the vacuumdiaphragm is properly installed.

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Diaphragm

Vacuum Chamber CoverSpring

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AGILITY CITY 125

Remove the needle holder and jet needle.

INSPECTIONInspect the needle for stepped wear.Inspect the vacuum piston for wear ordamage.Inspect the diaphragm for deterioration andtears.

ASSEMBLYInstall the vacuum piston/diaphragm in thecarburetor body.Install the spring and then install thevacuum chamber cover.Tighten the two screws.

Vacuum Chamber CoverVacuum Diaphragm

Jet Needle

Vacuum Diaphragm

Be careful not to damage the vacuumdiaphragm.

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5. FUEL SYSTEM

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AGILITY CITY 125

FLOAT CHAMBERDISASSEMBLYRemove the three float chamber screws andthe float chamber.

Loosen the float pin screw.Remove the float pin, float and float valve.

Remove the main jet, needle jet holder,needle jet, slow jet and pilot screw.

Clean the removed fuel jets with detergentoil and blow them open with compressedair.Blow compressed air through all passagesof the carburetor body.

Pilot Screw

Float ValveFloat

Float Pin

Float Chamber

Slow Jet

Main Jet

Needle Jet Holder

Needle Jet

Screws

• Be careful not to damage the fuel jetsand pilot screw.

• Before removing, turn the pilot screwin and carefully count the number ofturns until it seats lightly and thenmake a note of this.

• Do not force the pilot screw against itsseat to avoid seat damage.

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5. FUEL SYSTEM

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AGILITY CITY 125

INSPECTIONInspect the float valve and valve seat fordamage or clogging.Inspect the float valve and valve seatcontact area for stepped wear orcontamination.

ASSEMBLYInstall the slow jet, needle jet, needle jetholder, main jet and pilot screw.

Standard Opening:3±1/2 turns

Install the float valve, float and float pin.

FLOAT LEVEL INSPECTION

Measure the float level.Float Level: 17.0mm

This installation sequence is the reverse ofremoval. Float Level Gauge

Float Valve

• Check the operation of the float valveand float before this inspection.

• Measure the float level by placing thefloat level gauge on the float chamberface parallel with the main jet.

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Float Pin

Pilot Screw

Slow Jet

Main Jet

Needle Jet Holder

Needle Jet

Valve Seat

Float

Worn or contaminated float valve andvalve seat must be replaced because itwill result in float level too high due toincomplete airtightness.

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Return the pilot screw to the originalposition as noted during removal.

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5. FUEL SYSTEM

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AGILITY CITY 125

CARBURETOR INSTALLATIONTighten the drain screw.Install the carburetor onto the intakemanifold, aligning the tab on the carburetorwith the cutout in the intake manifold.Tighten the intake manifold band screw.Install the air cleaner connecting tube andtighten the band screw.Connect the throttle cable to the throttlewheel on the carburetor.Tighten the lock nut.

Connect the fuel tube and vacuum tube tothe carburetor.

Connect the auto bystarter wire connector.Perform the following inspections andadjustments:-Throttle grip free play ( 3-3)-Carburetor idle speed ( 3-5)Connect the auto TPS unit wire connector.

Auto Bystarter Wire Connector

Fuel Tube

Adjusting Nut

Intake Manifold Band

Air Cleaner ConnectingTube Band

Throttle Cable Lock Nut

Vacuum Tube

TPS Nuit

5. FUEL SYSTEM

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AGILITY CITY 125

PILOT SCREW ADJUSTMENT* ADJUSTMENT

A tachometer must be used when adjustingthe engine speed.Turn the pilot screw clockwise until it seatslightly and back it out to the specificationgiven.Standard Opening: 3±1/2 turns

Warm up the engine and adjust the throttlestop screw to obtain the specified idlespeed.Idle Speed: 1700±100rpmTurn the pilot screw in or out slowly toobtain the highest engine speed.Slightly accelerate several times to makesure that the idle speed is within thespecified range.If the engine misses or runs erratic, repeatthe above steps.

Pilot Screw

Throttle Stop Screw

• The pilot screw is factory pre-set andno adjustment is necessary. Duringcarburetor disassembly, note thenumber of turns of the pilot screw anduse as a reference when reinstalling it.

• Place the motorcycle on its main standon level ground for this operation.

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• The carburetor must be adjusted whenthe engine is warm and the autobystarter is closed.

• Do not force the pilot screw against itsseat to prevent damage.

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5. FUEL SYSTEM

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AGILITY CITY 125

FUEL TANK REMOVERemove the net-in box. ( 2-3)Remove the frame center cover.Remove the frame body cover. ( 2-3)Remove the four bolts on the fuel tank, takethe upper seat lock off.Disconnect the fuel unit wire connector.Remove the fuel tank.The installation sequence is the reverse ofremoval.

FUEL STRAINER REMOVALRemove the fuel strainer from the fuel tank.INSPECTIONInspect if the fuel strainer is clogged andclean it with compressed air.

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

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

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Arrow Mark

Fuel Strainer

Bolts Fuel Tank

Fuel Unit WiteConnector

5. FUEL SYSTEM

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AGILITY CITY 125

FUEL UNITREMOVALRemove the related parts.Disconnect the fuel unit wire connector.Turn the fixed plate on the fuel unit,take thefuel unit off.

INSTALLATIONInspet if the fuel unit is damaged,or harden.Assemble the fuel unit in the reverse orderof disassembly.

AIR CLEANERLoosen the air cleaner connecting tube bandscrew.Disconnect the clinhead cover breather tubefrom the air cleaner.Remove the two bolts and air cleaner case.

Fuel Unit Wire

Fuel Unit

Fuel Tank

Do not bend the float arm on the fuelunit,otherwise the figure on the fuelmeter will not correct.

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• Align the groove on the fuel unit withthe angle on the fuel tank.

• Inspect if the fuel tank leaked afterinstalling and filling the gasoling.

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bolts

air cleaner

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AGILITY CITY 125

TPS REMOVERemove the TPS stay screw.Remove the TPS and TPS stay assembled.

TPS UNIT INSPECTIONMeasure the TPS resistance betweenthe violet/black and green wire terminals.Measure the resistance:5KΩ±30％Measure the TPS resistance betweenthe violet/red and green wire terminals.Measure the resistance:5KΩ±30％

The installation sequence is the reverse of removal.

• While clean the carburetor, mustremove the TPS unit.

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Tps Unit

ScrewTPS Stay

• Whem measure the TPSresistance,carburetor throttle open themax place .

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Violet/BlackViolet/Red Green