By KWANG YANG Motor Co., Ltd. 1st Edition, Feb 2010 All ...This Service Manual describes the technical features and servicing procedures for the KYMCO MXU 250R/300R Section 1 contains

By KWANG YANG Motor Co., Ltd.1st Edition, Feb 2010

All rights reserved. Any reproduction orunauthorized use without the written permission of

KWANG YANG Motor Co., Ltd.is expressly prohibited.

T100-LC60AD

PREFACE

This Service Manual describes thetechnical features and servicingprocedures for the KYMCO MXU250R/300R

Section 1 contains the precautions forall operations stated in this manual.Read them carefully before starting anyoperation.

Section 2 is the removal/installationprocedures for the frame cover, whichare subject to higher removal/installationfrequency during maintenance andservicing operations.

Section 3 describes the inspection/adjustment procedures, safety rules andservice information for each part,starting from periodic maintenance.

Sections 4 through 19 give instructionsfor disassembly, assembly andinspection of engine, chassis frame andelectrical equipment.

Most sections start with an assembly orsystem illustration and troubleshootingfor the section. The subsequent pagesgive detailed procedures for the section.

KWANG YANG MOTOR CO., LTD.QUALITY TECHNOLOGY

DEPARTMENTTRAINING SERVICE SECTION

TABLE OF CONTENTSGENERAL INFORMATION 1FRAME COVERS/EXHAUST MUFFLER 2INSPECTION/ADJUSTMENT 3LUBRICATION SYSTEM 4FUEL SYSTEM 5

ENGINE REMOVAL 6CYLINDER HEAD/VALVES 7CYLINDER/PISTON 8DRIVE AND DRIVEN PULLEYS 9

FINAL REDUCTION/TRANSMISSIONSYSTEM 10

CRANKCASE/CRANKSHAFT/BALANCE SHAFT 11

COOLING SYSTEM 12BRAKE SYSTEM 13

FRONT WHEEL/FRONTSUSPENSION/STEERING SYSTEM 14

REAR WHEEL/AXLE/SUSPENSION/DRIVING MECHANISM 15

BATTERY/CHARGING SYSTEM/A.C.GENERATOR 16

IGNITION SYSTEM 17STARTING SYSTEM 18LIGHTS/SWITCHES 19

CH

ASSIS

ELECTR

ICA

LEQ

UIPM

ENT

ENG

INE

The information and contents includedin this manual may be different from theATV in case specifications are changed.KYMCO reserves the right to makechanges at any time without notice andwithout incurring any obligation.

1. GENERAL INFORMATION

1-0

MXU 250R/300R

1 __________________________________________________________________________________

__________________________________________________________________________________

__________________________________________________________________________________

__________________________________________________________________________________

__________________________________________________________________________________

GENERAL INFORMATION__________________________________________________________________________________

SERIAL NUMBER---------------------------------------------------------- 1- 1SPECIFICATIONS ---------------------------------------------------------- 1- 2SERVICE PRECAUTIONS ------------------------------------------------ 1- 4TORQUE VALUES --------------------------------------------------------- 1-12SPECIAL TOOLS ----------------------------------------------------------- 1-14LUBRICATION POINTS -------------------------------------------------- 1-15CABLE & HARNESS ROUTING ---------------------------------------- 1-18TROUBLESHOOTING----------------------------------------------------- 1-22

1


1-1

MXU 250R/300R

SERIAL NUMBER

Location of Engine Serial Number

Location of Frame Serial Number


1-2

MXU 250R/300R

SPECIFICATIONS (MXU 250R)

Model No. LG50ADName & Type MXU 250ROverall length 1980 mm (79.2 in)Overall width 1110 mm (44.4 in)Overall height 1100 mm (44.0 in)Wheel base 1200 mm (48.0 in)Engine type O.H.C.Displacement 249 cm3 (15.2 cu-in)Fuel Used 92# nonleaded gasoline

Front wheel 117 kg (257.4 lbs)Dry weight Rear wheel 105 kg (231 lbs)

Total 222 kg (488.4 lbs)Front wheel 124 kg (272.8 lbs)

Curb weight Rear wheel 112 kg (246.4 lbs)Total 236 kg (519.2 lbs)

Front wheel 22*7-10Rear wheel 22*10-10

Ground clearance 240 mm (9.6 in)Min. turning radius 2900 mm (116 in)

Starting system Electric/Recoil starterType Gasoline, 4-strokeCylinder arrangement Single cylinderCombustion chamber type Semi-sphereValve arrangement O.H.C., chain driveBore x stroke 72.7 x 60 mm

(2.9 x 2.4 in)Compression ratio 10.3:1

Compression pressure 15 kgf/cm² (1500kPa,213 psi)

Open 5° BTDCIntake valve(at 1 mm lift) Close 41° ABDC

Open 37° BBDCExhaust valve(at 1 mm lift) Close 5° ATDCValve clearance Intake 0.1 mm (0.004 in)(cold) Exhaust 0.1 mm (0.004 in)Idle speed (rpm) 1500 rpm

Lubrication type Forced pressure &Wet sump

Oil pump type TrochoidOil filter type Full-flow filtrationOil capacity 1.6 L (1.4 lmp qt, 1.7

Us qt)Oil exchangingcapacity

1.4 L (1.23 lmp qt,1.48 Us qt)

Cooling Type Liquid cooled

Air cleaner type & No Wet type element

Fuel capacity 12.5 L (2.63 lmpgal, 3.25 US gal

Type PDMain jet NO. 98Venturi dia. φ22 mm (φ0.88 in)Throttle type PISTON

Type Full transistordigital ignition

Ignition timing 5°BTDC/1000rpm

Spark plug DPR7EA-9

Spark plug gap 0.6～0.7mm (0.002～0.003 in)

Battery Capacity 12V14AH

Clutch type Dry, centrifugalautomatic

Clutch operation system Automatic (V-belt)

Primary reduction system Helical gear/spurgear

Secondary reduction system Chain driveForward drive high ratio 10.01~26.53Reverse ratio 19.21~50.92

FR/RR tire rollingcircumference

1733(K)/1767(M)-FR1743(K)/1796(M)-RR

FrontTire pressure(Rider only) Rear

0.28 kg/cm² (28Kpa, 3.2 psi)

Turning Left 36°angle Right 36°

Front Disk brakeBrake system typeRear Disk brake

Front Double A-ArmSuspension type

Rear Swing Arm

Frame type Double cradle

Tires

Fuel System

Carbureto r

Electrical Equipment

Ignition System

LubricationS ystem

Engine

Drive Train

Moving D

evice


1-3

MXU 250R/300R

SPECIFICATIONS (MXU 300R)

Model No. LC60ADName & Type MXU 300ROverall length 1980 mm (79.2 in)Overall width 1110 mm (44.4 in)Overall height 1100 mm (44.0 in)Wheel base 1200 mm (48.0 in)Engine type O.H.C.Displacement 270 cm3 (16.2 cu-in)Fuel used 92# nonleaded gasoline

Front wheel 117 kg (257.4 lbs)Rear wheel 105 kg (231 lbs)Dry weightTotal 222 kg (488.4 lbs)Front wheel 125 kg (275 lbs)Rear wheel 112 kg (246.4 lbs)Curb weightTotal 236 kg (519.2 lbs)Front wheel 22*7-10TiresRear wheel 22*10-10

Ground clearance 240 mm (9.6 in)Min. turning radius 3200 mm (128 in)

Starting systemElectric/Recoil

starterType Gasoline, 4-strokeCylinder arrangement Single cylinderCombustion chamber type Semi-sphereValve arrangement O.H.C., chain drive

Bore x stroke72.7 x 65.2 mm

(2.9 x 2.6 in)Compression ratio 11:1

Compression pressure 16 kgf/cm²(1600kPa, 227 psi)

Opens 9° BTDCIntake valve(at 1mm lift) Closes 40° ABDC

Opens 42° BBDCExhaust valve(at 1mm lift) Closes 7° ATDC

Intake 0.1 mm (0.004 in)Valve clearance(cold) Exhaust 0.1 mm (0.004 in)Idle speed (rpm) 1600 rpm

Lubrication type Forced pressure &Wet sump

Oil pump type TrochoidOil filter type Full-flow filtrationOil capacity 1.6 L (1.4 lmp qt,

1.7 Us qt)Oil exchangingcapacity

1.4 L (1.23 lmp qt,1.48 Us qt)

Cooling Type Liquid cooled

Air cleaner type & No Wet type element

Fuel capacity 12.5 L (2.63 lmp gal,3.25 US gal

Type CVKMain jet NO. 112Venturi dia. φ31 mm (φ1.24 in)Throttle type Valve Piston

Type Full transistor digitalignition

Ignition timing 5°BTDC/1500 rpmSpark plug DPR7EA-9

Spark plug gap 0.6～0.7mm (0.002 ～0.003 in)

Battery Capacity 12V14AH

Clutch type Dry, centrifugalautomatic

Clutch operation system Automatic (V-belt)

Primary reduction system Helical gear/spurgear/bevel gear

Secondary reductionsystem Driven mechanism

Forward Drive High Ratio 9.21 ~ 24.42Forward Drive Low Ratio 17.54 ~ 46.50Backward Drive Ratio 14.64 ~ 38.80FR/RR tire rollingcircumference

1733(K)/1767(M)-FR1743(K)/1796(M)-RR

FrontTire pressure (Rideronly) Rear

0.28 kg/cm² (28Kpa, 3.2 psi)

Left 36°Turning angleRight 36°

Front Disk brakeBrake system typeRear Disk brakeFront Double A-ArmSuspension typeRear Swing Arm

Frame type Double cradle

Engine

Lubrication System

Fuel SystemC

arburetor

Electrical Equipment

I gnition System

Drive Train

Moving D

evice


1-4

MXU 250R/300R

SERVICE PRECAUTIONS

Make sure to install new gaskets, O-rings,circlips, cotter pins, etc. when reassembling.

When tightening bolts or nuts, begin withlarger-diameter to smaller ones at severaltimes, and tighten to the specified torquediagonally.

Use genuine parts and lubricants.

When servicing the motorcycle, be sure touse special tools for removal andinstallation.

After disassembly, clean removed parts.Lubricate sliding surfaces with engine oilbefore reassembly.


1-5

MXU 250R/300R

Apply or add designated greases andlubricants to the specified lubricationpoints.

After reassembly, check all parts for propertightening and operation.

When two persons work together, payattention to the mutual working safety.

Disconnect the battery negative (-) terminalbefore operation.When using a spanner or other tools, makesure not to damage the motorcycle surface.

After operation, check all connecting points,fasteners, and lines for proper connectionand installation.When connecting the battery, the positive (+)terminal must be connected first.After connection, apply grease to the batteryterminals.Terminal caps shall be installed securely.


1-6

MXU 250R/300R

If the fuse is burned out, find the cause andrepair it. Replace it with a new oneaccording to the specified capacity.

After operation, terminal caps shall beinstalled securely.

When taking out the connector, the lock onthe connector shall be released beforeoperation.

Hold the connector body when connectingor disconnecting it.Do not pull the connector wire.

Check if any connector terminal is bending,protruding or loose.

ConfirmCapacity


1-7

MXU 250R/300R

The connector shall be insertedcompletely.If the double connector has a lock, lock itat the correct position.Check if there is any loose wire.

Before connecting a terminal, check fordamaged terminal cover or loosenegative terminal.

Check the double connector cover forproper coverage and installation.

Insert the terminal completely.Check the terminal cover for propercoverage.Do not make the terminal cover openingface up.

Secure wire harnesses to the frame withtheir respective wire bands at the designatedlocations.Tighten the bands so that only the insulatedsurfaces contact the wire harnesses.

Snapping!


1-8

MXU 250R/300R

After clamping, check each wire to makesure it is secure.

Do not squeeze wires against the weld or itsclamp.

After clamping, check each harness to makesure that it is not interfering with anymoving or sliding parts.

When fixing the wire harnesses, do notmake it contact the parts which willgenerate high heat.

Route wire harnesses to avoid sharp edgesor corners. Avoid the projected ends ofbolts and screws.Route wire harnesses passing through theside of bolts and screws. Avoid theprojected ends of bolts and screws.

No Contact !


1-9

MXU 250R/300R

Route harnesses so they are neitherpulled tight nor have excessive slack.

Protect wires and harnesses with electricaltape or tube if they contact a sharp edge orcorner.

When rubber protecting cover is used toprotect the wire harnesses, it shall beinstalled securely.

Do not break the sheath of wire.If a wire or harness is with a broken sheath,repair by wrapping it with protective tape orreplace it.

When installing other parts, do not press orsqueeze the wires.

Do not pulltoo tight!

Do not press orsqueeze the wire.


1-10

MXU 250R/300R

After routing, check that the wire harnessesare not twisted or kinked.

Wire harnesses routed along with handlebarshould not be pulled tight, have excessiveslack or interfere with adjacent orsurrounding parts in all steering positions.

When a testing device is used, make sure tounderstand the operating methodsthoroughly and operate according to theoperating instructions.

Be careful not to drop any parts.

When rust is found on a terminal, removethe rust with sand paper or equivalentbefore connecting.

Do you understandthe instrument? Is theinstrument setcorrectly?

Remove Rust !


1-11

MXU 250R/300R

Symbols:The following symbols represent theservicing methods and cautions included inthis service manual.

: Apply engine oil to thespecified points. (Usedesignated engine oil forlubrication.)

: Apply grease for lubrication.

: Transmission Gear Oil (90#)

: Caution

: Warning

Engine Oil

Grease

Gear Oil


1-12

MXU 250R/300R

TORQUE VALUES

STANDARD TORQUE VALUES

Item Torque kgf-m (N-m, lbf-ft) Item Torque

kgf-m (N-m, lbf-ft)5mm bolt and nut6mm bolt and nut8mm bolt and nut10mm bolt and nut12mm bolt and nut14mm bolt and nut

0.5 (5, 3.6)1 (10, 7.2)2.2 (22, 16)3.5 (35, 25)5.5 (55, 40)7 (70, 50)

4mm screw5mm screw6mm screw, SH bolt6mm flange bolt and nut8mm flange bolt and nut10mm flange bolt and nut

0.3 (3, 2.2)0.4 (4, 2.9)0.9 (9, 6.5)1.2 (12, 9)2.7 (27, 20)4 (40, 29)

Torque specifications listed below are for important fasteners.

ENGINE

Item Q‘ty Thread dia.(mm)

Torque kgf-m (N-m, lbf-ft)

Remarks

Stud boltOil filter screen capSeat ball stopper boltL cover boltCam shaft holder nutTappet ADJ nutPivot tensioner boltLifter tensioner boltLifter tensioner capMission case boltMission fill and drain boltDriver face nutClutch outer nutDrive plate nutACG flywheel nutSpark plugWater pump impellerOil drain plugOil pump screwHead CYL stud bolt (IN pipe)Head CYL stud bolt (EX pipe)A.C.G StartorDrive bevel gear nut (MXU 300)Driven bevel gear nut (MXU 300)

4111042121921111111122311

83014685866812141228141271236851816

0.9 (9, 6.5)1.5 (15, 11)4.8 (48, 35)1.2 (12, 8.6)2.5 (25, 18)0.9 (9, 6.5)1 (10, 7.2)

1.2 (12, 8.6)0.4 (4, 2.9)2.7 (27, 20)2 (20, 15)

9.5 (95, 68)5.5 (55, 40)5.5 (55, 40)6 (60, 43)

1.8 (18, 13)1.2 (12, 8.6)2.5 (25, 18)0.2 (2, 1.5)0.9 (9, 6.5)0.9 (9, 6.5)0.9 (9, 6.5)10 (100, 72)10 (100, 72)

Apply oilApply oil

Apply oil

Left thread


1-13

MXU 250R/300R

FRAME

Item Q‘ty Thread dia.(mm)

TorqueKgf-m (N-m, lbf-ft) Remarks

Steering stem nut

Front swing arm nut

Knuckle ball joint nut

Tie-rod ball joint nut

Front wheel nut

Rear wheel nut

Front wheel hub nut

Rear wheel hub nut

Front shock absorber upper mount bolt

Front shock absorber lower mount bolt

Rear shock absorber upper mount bolt

Rear shock absorber lower mount bolt

Right pivot bolt (MXU 300)

Left pivot bolt (MXU 300)

Left pivot lock nut (MXU 300)

Final gear case mounting bolt

Axle hub holding bolt (MXU 250)

Caliper holder bolt (MXU 250)

Rear wheel shaft nut (MXU 250)

Rear swingarm pivot bolt (MXU 250)

Rear engine upper mounting bolt

Rear engine lower mounting bolt

Front engine mounting bolt

Exhaust muffler lock bolt (frame)

Exhaust muffler lock nut (engine)

Brake caliper mounting bolt

Brake hose oil bolt

Master cylinder holder bolt

1

8

4

4

8

8

2

2

2

2

1

1

1

1

1

8

1

1

2

1

1

1

1

2

2

8

10

4

14

10

12

10

12

12

14

16

10

10

10

10

30

30

30

10

10

6

40

14

10

10

10

8

8

8

10

6

7 (70, 50)

4.5 (45, 32)

3 (30, 22)

2 (20, 15)

4.5 (45, 32)

4.5 (45, 32)

7 (70, 50)

10 (100, 72)

4 (40, 29)

4 (40, 29)

4 (40, 29)

4 (40, 29)

11.8 (118, 85)

1.1 (11, 8)

11.8 (118, 85)

5.5 (55, 40)

4 (40, 29)

1 (10, 7.2)

12 (120, 86)

7 (70, 50)

4 (40, 29)

4 (40, 29)

4 (40, 29)

3.5 (35, 25)

3.5 (35, 25)

3.2 (32, 24)

3.5 (35, 25)

1.2 (12, 8.6)

Castle nut

Castle nut

Castle nut

Castle nut


1-14

MXU 250R/300R

SPECIAL TOOLS


1-15

MXU 250R/300R

LUBRICATION POINTS

ENGINE

Lubrication Points Lubricant

Valve guide/valve stem movable part Cam lobes Valve rocker arm friction surface Cam chain Cylinder lock bolt and nut Piston surroundings and piston ring grooves Piston pin surroundings Cylinder inside wall Connecting rod/piston pin hole Connecting rod big end Crankshaft right side oil seal Crankshaft one-way clutch movable part Oil pump drive chain Balance gear A.C. generator Starter one-way clutch Bearing movable part O-ring face Oil seal lip

• Engine Oil (SAE10W-30) • API SE,SF,SG or higher Engine Oil

Transmission gear and rear driving mechanism Gear oil: SAE90#


1-16

MXU 250R/300R

FRAMEThe following is the lubrication points for the frame.Use general purpose grease for parts not listed.Apply clean engine oil or grease to cables and movable parts not specified. This will avoidabnormal noise and rise the durability of the ATV.

Steering Column UpperThrottle Cable

Steering Column Lower

Front Swing Arm BushFront Swing Arm


1-17

MXU 250R/300R

Sprocket hub/RearAxle Hub Collar/OilSeal/Bearing

Driven Sprocket

Rear Swing Arm Axle


1-18

MXU 250R/300R

CABLE & HARNESS ROUTING

Handlebar Switch Wire

Ignition SwitchConnector

Rear Brake Fluid Hose

Harness Wire

Motor Fan Wire/Thermostatic Switch Wire

Left Front Brake Fluid Hose

Right Front Brake Fluid Hose

Thermostatic SensorWire

Front Brake Fluid Hose

Stop Switch Cord

Throttle CableMulti-function Connector

Horn (ON ROAD)

Front Right TurnSignal Light (ONROAD)/HeadlightConnectors

Speed Cable

Front Left Turn Signal Light(ON ROAD)/HeadlightConnectors


1-19

MXU 250R/300R

Coolant ReservoirBreather Hose

Outlet Water Hose

Temperature Sensor Wire

Inlet Water Hose

Water Hose

CarburetorDrain Tube

Start MotorCable

Radiator OverflowTube

A.C.G Wire

REG.REC

Stop Switch Wire

Turn Signal Relay

Hazard Unit

Horn (ONROAD)

Headlight Control Unit

Gear ChangeSwitch Wire

A.C.G Connector

Gear ChangeSwitch Connector

Main Wire HarnessTurn Signal Light/StopLight Connectors (ONROAD)

License LightConnector(ON ROAD)

Ground Wire

Right TurnSignal Light(ONROAD)/TailLightConnector


1-20

MXU 250R/300R

Motor Fan Wire

Handlebar Switch Wire


Harness Wire

Blow By Hose


Start Motor Cable

Battery Cable

Crankcase Breather Hose


Ignition Coil

Throttle Cable Left Turn Signal Light (ONROAD)/ Tail Light Connector


1-21

MXU 250R/300R

Battery

Negative Terminal Cable

Positive Terminal Cable

Ignition Control Module

Starter Relay

Starter Motor Cable

Ground Wire

Gear Change Control Unit

Fuse Box


1-22

MXU 250R/300R

Hose Breeze of Battery


1-23

MXU 250R/300R

TROUBLESHOOTING

ENGINE WILL NOT START OR IS HARD TO START

Empty fuel tankClogged fuel line between fueltank and carburetorClogged float oil passageClogged fuel tank cap breatherholeClogged fuel filterClogged fuel valve passage

Faulty spark plugFouled spark plugFaulty ignition unitFaulty change gear control unitFaulty pulser coilBroken or shorted ignition coilBroken or shorted exciter coilFaulty ignition switchWeak or dead battery

Faulty starter clutchValve clearance too smallValve stuck openWorn cylinder, piston and pistonringsLeaking cylinder head gasket

Air leaking through intake pipeLeaking intake manifoldIncorrect ignition timingIncorrectly adjusted air screw

Flooded carburetorClogged air cleanerThrottle valve excessively open

Check if fuel reachescarburetor by looseningdrain screw

Remove spark plug andinstall it into spark plugcap to test spark byconnecting it to engineground

Inspection/Adjustment Probable Cause

Spark jumps

Normal compression

Engine does not fire

Weak or no spark

Low or no compression

Engine fires but does not start

Test cylindercompression

Start engine by follow-ing normal startingprocedure

Remove spark plug andinspect again

Symptom

Fuel reaches carburetor

Fuel does not reach carburetor

Wet spark plugDry spark plug


1-24

MXU 250R/300R

ENGINE LACKS POWER

Clogged air cleanerRestricted fuel flowClogged fuel tank cap breather holeClogged exhaust mufflerCarburetor fuel level too low

Faulty ignition unit

Faulty pulser coil

Improper valve clearanceadjustmentExcessively worn valve seat(protruded valve stem)

Improper valve and seat contactWorn cylinder and piston ringsLeaking cylinder head gasketImproper valve timing

Clean and unclog

Fouled spark plugIncorrect heat range plug

Oil level too highOil level too lowOil not changed

Clogged oil line

Faulty oil pump

Coolant level too lowWorn cylinder and piston ringsMixture too leanPoor quality fuelExcessive carbon build-up incombustion chamberIgnition timing too early

Excessive carbon build-up incombustion chamberPoor quality fuelClutch slippingMixture too leanIgnition timing too early

Start engine andaccelerate lightly forobservation

Inspection/Adjustment Symptom Probable Cause

Engine speedincreases

Correct timing

Engine speed does notincrease sufficiently

Incorrect timing

Check ignition timing(using a timing light)

Test cylinder compression

Check carburetor forclogging

Rapidly accelerate or runat high speed

Remove spark plug andinspect

Check if engine overheats

Check valve clearance

Correct Incorrect

Normal compression

Abnormal compression

Remove oil dipstick andcheck oil level and condition

Remove cylinder head oilpipe bolt and inspect

Engine overheats Engine does not overheats

Plug not fouled ordiscolored

Plug fouled or discolored

Correct and not contaminated

Incorrect or contaminated

Valve train lubricatedproperly

Valve train notlubricated properly

Engine does not knock Engine knocks

Not clogged Clogged


1-25

MXU 250R/300R

POOR PERFORMANCE (ESPECIALLY AT IDLE AND LOW SPEEDS)

Faulty ignition unitFaulty pulser coil

Mixture too rich (turn screwout)

Mixture too lean (turn screw in)

Deteriorated O-ringCarburetor not securelytightenedDamaged insulator rubber

Faulty or fouled spark plugFaulty ignition unitFaulty A.C. generatorFaulty ignition coilBroken or shorted spark plugwireFaulty ignition switch

Remove spark plug andinstall it into spark plugcap to test spark byconnecting it to engineground


Check ignition timing

Check carburetor gasketfor air leaks

Check carburetor airscrew adjustment

Correct timing Incorrect timing

Correctly adjusted

No air leak Air leaks

Good spark Weak or inter- mittent spark

Incorrectly adjusted


1-26

MXU 250R/300R

POOR PERFORMANCE (AT HIGH SPEED)

Faulty ignition unitFaulty pulser coil

Improperly adjusted valveclearanceWorn valve seat

Empty fuel tankClogged fuel tube or filter

Clogged Fuel tank cap breatherhole

Clean and unclog

Cam timing gear aligning marksnot aligned

Faulty spring


Check ignition timing

Check carburetor jetsfor clogging

Check fuel pump forfuel supply

Correct timing Incorrect timing

Check valve springtension

Check valve clearance

Fuel flows freely Fuel flow restricted

Correct Incorrect

Not clogged Clogged

Correctly adjusted Incorrectly adjusted

Not weakened Weak spring

Check valve timing


1-27

MXU 250R/300R

POOR CHARGING (BATTERY OVER DISCHARGING OR OVERCHARGING)

Undercharging

Dead batteryFaulty battery

Faulty A.C. generator coilBroken yellow wireShorted pink and yellowwires

Broken red wire

Faulty regulator/rectifierPoorly connected coupler

Faulty A.C. generator

Overcharging

Broken green wire

Poorly connected coupler

Faulty regulator/rectifier

Start engine and testlimit voltage of batteryterminals

Connect battery (+) wireto regulator/rectifiercoupler red wire andbattery (-) wire to engineground and test voltage

Inspection/Adjustment

Inspection/Adjustment

Symptom

Symptom

Probable Cause

Probable Cause

Normal voltage

Battery has voltagewith ignitionswitch “ON”

Normal

Voltage does notincrease

Battery has novoltage with ignitionswitch “ON”

Resistance too high

Normal voltage No voltage

Measure resistancebetween AC generatorcoil terminals

Normal Abnormal

Check regulator/rectifiercoupler for looseconnection

Normal Abnormal

Connect battery (+) wireto regulator/rectifiercoupler green wire andbattery (-) wire to engineground and test voltage

Check regulator/rectifiercoupler for looseconnection


1-28

MXU 250R/300R

NO SPARK AT SPARK PLUG

Faulty spark plug

Loose spark plug cap

Poorly connected coupler

Faulty ignition switchWeak batteryFaulty pulser coilFaulty ignition coilFaulty charging system

Broken wire harnessPoorly connected coupler

Faulty ignition unitFaulty change gear controlunit

Faulty ignition coil

Replace with a newspark plug and inspectagain

Check ignition unitcoupler for looseness


Normal

Abnormal

Normal

Abnormal

Normal Abnormal

Abnormal

Measure resistancebetween terminals ofignition unit coupler

Check related parts

Check ignition coil witha ignition unit tester

Weak or no spark

Not loose

Good spark

Loose

Good Good

Check spark plug capand high-tension wirefor looseness

Check ignition unitwith a ignition unittester

Documents

By KWANG YANG Motor Co., Ltd. 1st Edition, Feb 2010 All ...This Service Manual describes the technical features and servicing procedures for the KYMCO MXU 250R/300R Section 1 contains