BAJA WILDERNESS WD250U ATV Service Repair Manual
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WD250U Service Manual
For any questions please contact Baja Motorsports at 888-863-2252
Content
Content...........................................................................................................................2
Chapter I General description........................................................................................6
Section 2 Special tools, instruments & meters.............................................................. 7
(I) Special tools....................................................................................................7
Section 3 Identification code, label of model and engine No........................................9
Section 4 Points for attention in maintenance................................................................9
Section 5 Specification................................................................................................. 13
I. How to use conversion table of unit............................................................... 13
(1) How to use conversion table........................................................................ 13
(2) Definition of unit..........................................................................................13
II. Basic specification.........................................................................................14
III. ATV body ..................................................................................................... 15
IV. Electric system............................................................................................. 16
V. Maintenance specification of engine............................................................. 18
Section 6 Wiring diagram of ATV ................................................................................ 21
(I) Technical explanation and requirement, details of relative component........ 21
(II) Wiring diagram (1)...................................................................................... 23
(III) Wiring diagram (2)..................................................................................... 24
(IV) Wiring diagram (3)..................................................................................... 25
Section 7 Requirements for torque of fastener ............................................................. 26
(1) ATV body ..................................................................................................... 26
(2) Engine.......................................................................................................... 28
(3) General torque specification........................................................................ 30
Section 8 Lubrication................................................................................................... 31
(1) Lubrication oil way ........................................................................................31
(2) Lubrication diagram..................................................................................... 32
Section 9 Lubrication point and type of lubricants...................................................... 34
(1) ATV body ..................................................................................................... 34
(2) Engine.......................................................................................................... 35
Chapter II Maintenance and adjustment of vehicle...................................................... 36
Section 1 Periodic maintenance/lubrication................................................................ 36
Section 2 Disassembly and assembly of cushion, fender and fuel tank....................... 37
(I) Cushion......................................................................................................... 37
(II) Rear fender .................................................................................................. 38
(III) Fuel tank..................................................................................................... 40
(IV) Front fender ................................................................................................ 42
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Section 3 Maintenance and adjustment of vehicle body .................................................................... 44
(I) Wear inspection of front and rear brake............................................................................ 44
(II) Adjustment of front brake..................................................................................................44
(III) Adjustment of free clearance of left lever and rear brake pedal.......................................45
(IV) Position adjustment of steering lever ............................................................................. 47
(V) Lubricating oil level inspection of rear driving gearcase................................................. 47
(VI) Replacement of engine oil of rear driving gearcase....................................................... 48
(VII) Rubber sleeve inspection of rear wheel fork................................................................. 49
(VIII) Inspection of steering system....................................................................................... 49
(IX) Adjustment of toe-in of front wheel............................................................................... 50
(X) Inspection of front/rear shock absorber ........................................................................... 51
(XI) Adjustment of rear shock absorber ............................................................................... 51
(XII) Inspection of tire.......................................................................................................... 52
(XIII) Inspection of rim........................................................................................................ 53
Section 4 Maintenance and adjustment of electrical appliance......................................................... 54
(I) Inspection of battery ......................................................................................................... 54
(II) Inspection of fuse............................................................................................................ 55
(III) Replacement of headlight lamp.......................................................................................56
Section 5 Maintenance and adjustment of engine.............................................................................. 58
(I) Adjustment of clutch......................................................................................................... 58
(II) Cleaning of air filter .........................................................................................................58
(III) Inspection of spark plug................................................................................................. 60
(IV) Adjustment of idle speed.............................................................................................. 61
(V) Adjustment of free clearance of throttle grip................................................................. 61
(VI) Adjustment of speed limiter ........................................................................................... 62
(VII) Adjustment of valve clearance.................................................................................... 63
(VIII) Adjustment of timing chain tension.............................................................................65
(IX) Inspection of ignition timing........................................................................................ 66
(X) Measuring of compressive force..................................................................................... 67
(XI) Inspection oil quantity of engine................................................................................... 68
(XII) Replacement of engine oil and inspection of oil flow .................................................. 69
Chapter III Repair and maintenance of vehicle body .........................................................................71
Section 1 Rear driving gearcase and driving shaft.............................................................................71
(I) Troubleshooting.................................................................................................................72
(II) Inspection.........................................................................................................................72
(III) Troubleshooting table.....................................................................................................73
(IV) Disassembly .................................................................................................................. 74
(V) Inspection.........................................................................................................................77
(VI) Pad choice of main driving gear and shift gear ............................................................ 79
(VII) Installation....................................................................................................................80
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Section 3 Rear wheel/Rear brake/Rear wheel axle................................................................ 81
(I) Removal steps....................................................................................................... 83
(II) Inspection stepes.................................................................................................. 85
(III) Installation steps................................................................................................. 88
Section 4 Steering operation system...................................................................................... 92
(I) Removal steps of steering bar ................................................................................ 93
(II) Removal steps of steering vertical column welding............................................ 94
(III) Inspection content............................................................................................... 95
(IV) Installation steps................................................................................................. 96
(V) Installation steps of steering bar .......................................................................... 99
Section 5 Front shock absorber and front wheel fork............................................................ 100
(I) Disassembly ........................................................................................................... 101
(II) Inspection steps.................................................................................................... 103
(III) Installment steps................................................................................................. 104
Section 6 Rear shock absorber and rear wheel fork............................................................... 107
(I) Disassembling steps.............................................................................................. 108
(II) Checking steps..................................................................................................... 110
(III) Mounting steps................................................................................................... 112
Chapter IV Electric appliance................................................................................................ 115
Section 1 Electric assembly .................................................................................................... 115
Section 2 Inspect switch......................................................................................................... 116
(I) Inspect switch........................................................................................................ 116
(II) Inspect the switch circuit..................................................................................... 117
Section 3 Check headlight lamp............................................................................................. 118
Wire diagram.............................................................................................................. 119
Section 4 Troubleshooting the ignition system failure........................................................... 120
Section 5 Running starting circuit.......................................................................................... 124
Section 6 Troubleshooting electric starting system................................................................ 125
Section 7 Starting motor ......................................................................................................... 128
Section 8 Check starting motor ............................................................................................... 129
Section 9 Battery will not hold charge.................................................................................... 131
Section 10 Troubleshooting.................................................................................................... 133
Section 11 Inspection of lighting system................................................................................ 135
(I) Headlight not working........................................................................................... 135
(II) Taillight not working............................................................................................ 136
Section 12 Troubleshooting.................................................................................................... 137
(I) If indicated lamp is out of work............................................................................. 137
Section 13 Inspection of signal system.................................................................................. 139
(I) If the neutral indicated lamp is out work............................................................... 139
(II) If the reverse indicated lamp is out work............................................................. 140
(III) If the HB indicated lamp is out work.................................................................. 141
Chapter V Engine................................................................................................................... 142
Section 1 Disassembly of Engine........................................................................................... 142
(I) Remove the engine from finished ATV .................................................................. 142
(II) Disassembly of engine......................................................................................... 145
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Section 2 Inspection and maintanence of engine............................................................................... 159
Section 3 Assembly and adjustment of engine................................................................................... 183
(I) Closing assembly of left & right crankcase...................................................................... 183
(II) Assembly of right crankcase............................................................................................ 187
(III) Assembly of left crankcase............................................................................................. 196
(IV) Selection and installation of adjusting washer ............................................................... 207
(V) Assembly of cylinder head.............................................................................................. 209
(VI) Manual starting mechanism and others.......................................................................... 209
(VII) Mount the engine on the finished vehicle..................................................................... 219
Chapter VI Vehicle Troubleshooting.................................................................................................. 220
(I) Starting trouble/difficulty ................................................................................................... 227
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Chapter I General Description
Section 1 Description
1. Front wheel
2. Headlight
3. Forward/Reverse lever
4. Shift pedal
5. Fuel valve
6. Hand-operated lever
7. Air choke
8. Taillight
9. Rear wheel
10. Rear luggage carrier
11. Exhaust silencer
12. Cushion
13. Fuel tank cover
14. Rear brake pedal
15. Front luggage carrier
16. Left rear brake lever
17. Hand-operated parking brake
18. Main switch lock
19. Throttle grip
20. Right front brake lever
21. Left switch unit
22. Left and right mirror
CAUTION:
The ATV you purchased may be slightly different from the pictures in the
manual due to improvements.
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Section 2 Special tools, instruments and meters
(I) Special tools
There are special tools needed to properly adjust and assemble this unit. These tools are
intended to prevent maintenance defects and damage.
1. Wrench for valve adjustment, mainly used to adjusting the valve clearance. Specification:
3mm, 90890-01311
2. Puller for piston pin, used for removing piston pin.
3. Remover for rotator, mainly for pulling the magneto rotator from crank.
4. Clamp for rotator, for clamping magneto rotator when removing it to prevent it’s rotation due
to torque force.
5. Stop rotating meter for rotator, used for removing and assembling rotator of kick starter.
6. Puller for crank, for disassembling crank from crankcase.
7. Puller for rocker shaft, used for the removing rocker shaft.
8. Compressing tools for spring of valve, for fixing and compressing spring when assembling
valve lock clamp.
9. Assembling and disassembling tools for valve guide.
10. Assembling buffer, used for assembling crank and balancing gear.
11. Hollow sleeve, for assembling crank and balancing gear.
12. Assembling tool for crank, used for assembling crank and balancing gear.
13. Assembling and disassembling joint for universal coupling.
14. Assembling and disassembling disc, used for assembling and disassembling reverse gear.
15. Fixed puller for gear.
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(II) Instruments and meters
The following instruments and meters can be selected with
reference to the same type of vehicle.
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Section 3 Identification code, label
of model and engine No.
Identification code
Engraved in the left or right side of the front
supporting main tube of engine of frame
Engine No.
This is engraved on the top middle part of the
right crankcase of engine.
Section 4 Points for attention in maintenance
1. Preparation when disassembling
1.1 First clean the dirt and mud from the vehicle before removing or disassebmling.
1.2 Use proper cleaning device and tools.
1.3 Keep all the components away from fire. Pay attention to hot surfaces such as the engine,
exhuast etc.
1.4 When disassembling the ATV, keep alike parts such as gear pairs, cylinder, piston, etc.
together. When assembling or replacing these components they should be kept in pairs.
1.5 When disassembling the engine, clean all components and place in a tray in the order of dis-
assembly, not only increasing the assembling speed, but also ensuring the correct assembly.
2. Replace the components
When replacing components use only the products, lubricants and grease recommened by manu-
facturer.
3. Oil seal, shim, O-ring, clip, split pin, elastic washer
3.1 When disassembling to maintain the engine, to ensure that the reassembled engine has good
sealing and connected parts are fixed and reliable, the oil seal, shim, o-ring, clip, split pin and
elastic washer should be replaced, be sure to keep lip of oil seal, surface of shim and o-ring in a
clean condition.
3.2 When reassembling, apply lubricant to all the alike components and bearings,
apply grease for oil seal.
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4. Clip
4.1 Before assembling, check all the clips carefully.
Replace with a new one after removing from piston
pin. When mounting clip ring (1), make the sharp
end face (2) on the opposite position of
impacted face (3) of clip. (see figure at left)
5. Locking washer/shim and location pin
5.1 When reassembling, replace all locking washer/
shim and location pin (a) . After bolt or nut is in the
lock position, bend and fix both ends of locking shim
along head of bolt or direction of nut.
6. Bearing and oil seal
6.1 When assembling bearing and oil seal, put the
mark (specification of manufacturer) outside. When
assembling oil seal, apply a thin layer of lithium-
based grease on the lip of oil seal.
CAUTION:
Do not dry inside of bearing by blowing out with
compressed air, this will cause damage to the surface
of the bearing.
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