4. FUEL SYSTEM

4-0

Pulsar UP 125

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4. FUEL SYSTEM

4-1

Pulsar UP 125

SERVICE INFORMATIONGENERAL INSTRUCTIONS

• 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 reassembly.• 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.• 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.• 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 StandardVenturi dia. φ22Identification number PDFloat level 12.5 mmMain jet 92#Control method PistonIdle speed 1700±100rpmThrottle grip free play 2～6mmPilot screw opening 11/2~2

SPECIAL TOOLFloat level gauge

SERVICE INFORMATION.......................4-1 FLOAT LEVEL INSPECTION...............4- 6

TROUBLESHOOTING .............................4-2 CARBURETOR INSTALLATION ........4- 7

THROTTLE VALVE DISASSEMBLY ....4-3 THROTTLE VALVE ASSEMBLY........4- 7

CARBURETOR REMOVAL.....................4-3 FUEL TANK/FUEL VALVE..................4- 8

FLOAT/FLOAT VALVE/JETS/ AIR CLEANER .......................................4-10ACCELERATING PUMP..........................4-4

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.

4. FUEL SYSTEM

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Pulsar UP 125

TROUBLESHOOTING

Engine cranks but won’t start Engine lacks power• No fuel in tank • Clogged air cleaner• No fuel to carburetor • Faulty carburetor• Cylinder flooded with fuel • Faulty ignition system• No spark at plug• Clogged air cleaner Lean mixture• Intake air leak • Clogged carburetor fuel jets• Improper throttle operation • Float level too low

• Intake air leakEngine idles roughly, stalls or runs poorly • Clogged fuel tank cap breather hole• Excessively used choke • Kinked or restricted fuel line• Ignition malfunction• Faulty carburetor Rich mixture• Poor quality fuel • Float level too high• Lean or rich mixture • Clogged air jets• Incorrect idle speed • Clogged air cleaner

• Restricted A.C.V. tubeMisfiring during acceleration• Faulty ignition system• Faulty carburetor• Faulty accelerating pump

Backfiring at deceleration• Float level too low• Incorrectly adjusted carburetor• Faulty A.C.V.• Faulty exhaust muffler

4. FUEL SYSTEM

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Pulsar UP 125

THROTTLE VALVE DISASSEMBLYRemove the side cover.Remove the carburetor cap.Pull out the throttle valve.Disconnect the accelerating pump cable.

Disconnect the throttle cable and remove thespring from the throttle valve.

Pry off the needle retainer and remove the jetneedle.Check the throttle valve and jet needle forwear or damage.

CARBURETOR REMOVALSwitch the fuel valve OFF.Loosen the drain screw to drain the gasolinefrom the float chamber.

Throttle Valve

Drain Screw

Carburetor Cap

Needle Retainer

SpringThrottle Valve

Jet Needle

Clip

• Keep sparks and flames away from thework area.

• Drain gasoline into a clean container.

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Throttle Cable

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Pulsar UP 125

Loosen the air cleaner connecting tube bandscrew.Remove the two carburetor lock nuts.Remove the carburetor

FLOAT/FLOAT VALVE/JETS/FLOAT/FLOAT VALVE DISASSEMBLYRemove the three float chamber attachingscrews and remove the float chamber.

Remove the float pin, float and float valve.

FLOAT/FLOAT VALVE INSPECTIONInspect the float valve seat for wear ordamage.Inspect the float for damage or fuel levelinside the float chamber.

Float Valve Float Pin

Float

Screw Lock Nuts

Screws

Float ValveFloat Valve Seat

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Pulsar UP 125

JETS/AIR SCREW/THROTTLE STOPSCREW REMOVALRemove the main jet.Remove the slow jet.Remove the P.S screw and throttle stopscrew.

CAUTIONS !

CARBURETOR CLEANINGBlow compressed air through all passages ofthe carburetor body.

• Be careful not to damage the jets whenremoving them.

• Before removal, turn the throttle stopscrew and air screw in and count thenumber of turns until they seat lightlyand then make a note of this.

• Do not force the screw against its seatto avoid seat damage.

• Be sure to install the O-ring in thereverse order of removal.

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SpringWasherO-ring P.S Screw

Slow Jet Main JetThrottleStop Screw

Spring

P.S Screw

Slow Jet Main Jet

Throttle Stop Screw

4. FUEL SYSTEM

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Pulsar UP 125

SLOW/MAIN JET INSTALLATIONInstall the slow jet.Install the needle jet and main jet.Install the throttle stop screw and air screw.

Install the float valve, float and float pin.

FLOAT LEVEL INSPECTIONTurn the carburetor upside down so that thefloat will go down to make the float valvecontact the float valve seat.Then slowly tilt the carburetor and measurethe float level with the float level gaugewhile the float pin just contacts with floatvalve.

Float Level: 12.5mm

When adjusting, carefully bend the float pin.Check the float for proper operation and theninstall the float chamber.

Float Level Gauge

• When installing the air screw, return itto the original position as noted duringremoval.

• After the carburetor is installed, besure to perform the Exhaust EmissionTest.

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Float Pin

Float

P.S Screw

Slow Jet Main Jet

Throttle Stop Screw

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Pulsar UP 125

CARBURETOR INSTALLATIONInstall the carburetor onto the intakemanifold and tighten the two lock nuts.Torque: 0.8～1.2kg-mInstall the air cleaner connecting tube andtighten the band screw.

THROTTLE VALVE ASSEMBLYInstall the jet needle into the throttle valveand secure with the needle retainer.

Assemble the rubber cover, carburetor capand throttle valve spring.Connect the throttle cable to the throttlevalve.

Groove

Jet Needle

Needle RetainerClip

Carburetor Cap

Spring

Rubber Cover

Throttle Valve

Throttle Valve

Needle Retainer

Jet Needle

Clip

Screw Lock Nuts

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Pulsar UP 125

Install the throttle valve into the carburetorbody.

Connect the accelerating pump cable.Fully open the throttle and adjust theaccelerating pump cable to align the punchmark on the accelerating pump arm with thepunch mark on the set plate.

Tighten the carburetor cap.Inspect the throttle grip free play and adjustif necessary.Throttle Grip Free Play: 2～6mm

FUEL TANK/FUEL VALVEFUEL TANK REMOVAL

Remove the right and side covers.Remove the two lock nuts attaching the seatand remove the seat.

Switch the fuel valve “OFF”.Disconnect the fuel tube and remove the bolton the end of the fuel tank.Disconnect the fuel unit wire connector.Remove the fuel tank.

Fuel Unit Wire Connector

Lock Bolts

Throttle Stop Screw

Align the groove in the throttle valvewith the throttle stop screw on thecarburetor body.

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Groove

Carburetor Cap

• Keep sparks and flames away from thework area.

• Wipe off any spilled gasoline.

Warning

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Pulsar UP 125

FUEL VALVE REMOVALRemove the fuel valve body lock nut.Remove the fuel valve strainer.Remove the fuel valve.

INSPECTIONInspect the fuel valve strainer for dirt andclog. Clean if necessary.Replace the O-rings with new ones if theyare damaged or deteriorated.

FUEL TANK/FUEL VALVEINSTALLATIONInstall the fuel tank and fuel valve in thereverse order of removal.Check that there is no fuel leakage.Check the wire connectors for properconnection.

Fuel Valve

O-ring

Fuel Valve Body

Strainer

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Pulsar UP 125

AIR CLEANERREMOVALRemove the seat.Remove the two air cleaner case attachingbolts.Loosen the air cleaner and carburetorconnecting tube band screw.Remove the air cleaner case.

Remove the four air cleaner case coverscrews and the cover.Remove the air cleaner screen and element.

Bolts

Screws

Screw