2006 YAMAHA YZ250LC steering

CHAPTER 4
ENGINE
SEAT, FUEL TANK AND SIDE
COVERS.....................................................4-1
EXHAUST PIPE AND SILENCER..............4-3
RADIATOR..................................................4-4
CARBURETOR AND REED VALVE...........4-7
CYLINDER HEAD , CYLINDER AND
PISTON.....................................................4-18
CLUTCH AND PRIMARY DRIVEN
GEAR.......................................................4-33
KICK AXLE, SHIFT SHAFT AND
PRIMARY DRIVE GEAR...........................4-40
YPVS GOVERNOR...................................4-49
WATER PUMP..........................................4-52
CDI MAGNETO.........................................4-56
ENGINE REMOVAL..................................4-60
CRANKCASE AND CRANKSHAFT.........4-65
TRANSMISSION, SHIFT CAM AND
SHIFT FORK.............................................4-72
CHAPTER 5
CHASSIS
FRONT WHEEL AND REAR WHEEL........5-1
FRONT BRAKE AND REAR BRAKE.......5-10
FRONT FORK...........................................5-26
HANDLEBAR............................................5-42
STEERING................................................5-50
SWINGARM..............................................5-55
REAR SHOCK ABSORBER.....................5-63
1P8-9-31-0 5/12/05 10:58 AM Page 20

GEN
INFO
1-2
MACHINE IDENTIFICATION
EC120001
MACHINE IDENTIFICATION
There are two significant reasons for knowing
the serial number of your machine:
1. When ordering parts, you can give the num-
ber to your Yamaha dealer for positive iden-
tification of the model you own.
2. If your machine is stolen, the authorities will
need the number to search for and identify
your machine.
EC121001
VEHICLE IDENTIFICATION NUMBER
(For USA, CDN, AUS, NZ and E)
The vehicle identification number 1is stamped
on the right of the steering head pipe.
EC122001
FRAME SERIAL NUMBER
(For F, D, GB, I and ZA)
The frame serial number 1is stamped on the
right of the steering head pipe.
EC123001
ENGINE SERIAL NUMBER
The engine serial number 1is stamped into the
elevated part of the right-side of the engine.
EC124000
MODEL LABEL
The model label 1is affixed to the frame under
the rider’s seat. This information will be needed
to order spare parts.
1P8-9-31-1 5/12/05 11:01 AM Page 4

1-8
SPECIAL TOOLS
GEN
INFO
Part number Tool name / How to use IIIustration
YU-33975, 90890-01403 Ring nut wrenchYU-33975 90890-01403
This tool is used when tighten the steering ring nut
to specification.
YM-01500, 90890-01500 Cap bolt wrench
YM-01500 90890-01500
This tool is used to loosen or tighten the base valve.
YM-01501, 90890-01501 Cap bolt ring wrench
YM-01501 90890-01501
This tool is used to loosen or tighten the damper
assembly.
YM-A0948, 90890-01502 Fork seal driver
YM-A0948 90890-01502
This tool is used when install the fork oil seal.
YU-3112-C, 90890-03112 Yamaha pocket tester
YU-3112-C 90890-03112
Use this tool to inspect the coil resistance,
output voltage and amperage.
YU-8036-B Inductive tachometer
YU-8036-B 90890-03113
90890-03113 Engine tachometer
This tool is needed for observing engine rpm.
YM-91042, 90890-04086 Clutch holding tool
YM-91042 90890-04086
This tool is used to hold the clutch when removing
or installing the clutch boss securing nut.
YM-34487 Dynamic spark tester
YM-34487 90890-06754
90890-06754 Ignition checker
This instrument is necessary for checking the igni-
tion system components.
ACC-QUICK-GS-KT Quick gasket
®ACC-QUICK-GS-KT 90890-85505
90890-85505 YAMAHA Bond No. 1215
This sealant (Bond) is used for crankcase mating
surface, etc.
1P8-9-31-1 5/12/05 11:02 AM Page 15

1-16
TORQUE-CHECK POINTS
GEN
INFO
EC1A0013
TORQUE-CHECK POINTS
Frame construction Frame to rear frame
Combined seat and tank Fuel tank to frame
Engine mounting Frame to engine
Engine bracket to engine
Engine bracket to frame
Steering Steering shaft to Steering shaft to frame
handlebar Steering shaft to handle crown
Handle crown to handlebar
Suspension Front Steering shaft to Front fork to handle crown
front fork Front fork to under bracket
Rear For link type Assembly of links
Link to frame
Link to shock absorber
Link to swingarm
Rear Installation of shock Shock absorber to frame
absorber
Rear Installation of swingarm Tightening of pivot shaft
Wheel Installation of wheel Front Tightening of front axle
Tightening of axle holder
Rear Tightening of rear axle
Wheel to sprocket
Brake Front Caliper to front fork
Brake disc to wheel
Tightening of union bolt
Master cylinder to handlebar
Tightening of air bleeder
Tightening of brake hose holder
Rear Brake pedal to frame
Brake disc to wheel
Tighening of union bolt
Master cylinder to frame
Tightening of air bleeder
Tightening of brake hose holder
Fuel system Fuel tank to fuel cock
NOTE:
Concerning the tightening torque, refer to “
MAINTENANCE SPECIFICATIONS” section in
the CHAPTER 2.
1P8-9-31-1 5/12/05 11:02 AM Page 36

2-7
MAINTENANCE SPECIFICATIONSSPEC
EC212201
CHASSIS
Item Standard Limit
Steering system:
Steering bearing type Taper roller bearing…
Front suspension: USA, CDN, ZA,
EUROPE
AUS, NZ
Front fork travel
300 mm (11.8 in)←…
Fork spring free length
454 mm (17.9 in)←449 mm (17.7 in)
Spring rate, STD K=4.2 N/mm←…
(0.428 kg/mm,
24.0 lb/in)
Optional spring Yes←…
Oil capacity 527 cm
3532 cm3…
(18.6 Imp oz, (18.7 Imp oz,
17.8 US oz) 18.0 US oz)
Oil grade Suspension oil ←…
“S1”
Inner tube outer diameter 48 mm (1.89 in)←…
Front fork top endZero mm (Zero in)←…
Rear suspension: USA, CDN, ZA,
EUROPE
AUS, NZ
Shock absorber travel
131.5 mm (5.18 in)←…
Spring free length
Approx. 265 mm←…
(10.43 in)
Fitting length
One I.D. paint mark One I.D. paint mark
255 mm (10.04 in) 252 mm (9.92 in)…
Two I.D. paint marks Two I.D. paint marks
261 mm (10.28 in) 258 mm (10.16 in)…
Three I.D. paint marks Three I.D. paint marks
252.5 mm (9.94 in)249.5 mm (9.82 in)…

One I.D. paint mark
245.5 ~ 263.5 mm←…
(9.67 ~ 10.37 in)
Two I.D. paint marks
251.5 ~ 269.5 mm←…
(9.90 ~ 10.61 in)
Three I.D. paint marks
243.0 ~ 261.0 mm←…
(9.57 ~ 10.28 in)
Spring rate, STDK=48.0 N/mm ←…
(4.90 kg/mm,
274.4 lb/in)
Optional spring Yes←…
Enclosed gas pressure 1,000 kPa ←…
(10 kg/cm
2,
142 psi)
Swingarm:
Swingarm free play limit
End…
1.0 mm (0.04 in)
Side clearance…
0.2~0.9 mm
(0.008~0.035 in)
1P8-9-31-2 5/19/05 10:30 AM Page 8

2-9
MAINTENANCE SPECIFICATIONSSPEC
17
14
105
20
29
22
40
21
21
0.7
5.1
5.1
0.7
2.9
2.9
2.9
6.5
1.4
4.3
4.3
3.6
2.9
22
22
17
7.2
2.2
13
4.3
75
17
8.7
10
40
19
7.2M 8 × 1.25
M 8 × 1.25
M24 × 1.0
M 8 × 1.25
M12 × 1.25
M28 × 1.0
M51 × 1.5
M22 × 1.25
M42 × 1.5
M12 × 1.25
M 5 × 0.8
M 6 × 1.0
M 6 × 1.0
M 4 × 0.7
M 6 × 1.0
M 6 × 1.0
M 5 × 0.8
M 6 × 1.0
M 4 × 0.7
M 6 × 1.0
M 6 × 1.0
M 6 × 1.0
M 6 × 1.0
M10 × 1.25
M10 × 1.25
M 8 × 1.25
M 6 × 1.0
M10 × 1.0
M10 × 1.0
M 8 × 1.25
M16 × 1.5
M 8 × 1.25
M 6 × 1.0
M 6 × 1.0
M10 × 1.25
M 8 × 1.25
M 6 × 1.0 Handle crown and outer tube
Under bracket and outer tube
Handle crown and steering shaft
Handlebar holder (upper)
Handlebar holder (lower)
Steering ring nut
Front fork and damper assembly
Front fork and adjuster
Damper assembly and base valve
Adjuster and damper assembly
Bleed screw (front fork) and base valve
Front fork and protector
Protector and brake hose holder
Throttle cable cap
Grip cap upper and lower
Clutch lever (nut)
Clutch lever holder
Front brake master cylinder and bracket
Front brake master cylinder cap
Brake lever mounting (bolt)
Brake lever mounting (nut)
Brake lever position locknut
Cable guide (front brake hose) and under bracket
Front brake hose union bolt (master cylinder)
Front brake hose union bolt (caliper)
Front brake caliper and front fork
Front brake caliper and brake hose holder
Brake caliper (front and rear) and pad pin plug
Brake caliper (front and rear) and pad pin
Brake caliper (front and rear) and bleed screw
Front wheel axle and nut
Front wheel axle holder
Front brake disc and wheel hub
Rear brake disc and wheel hub
Footrest bracket and frame
Brake pedal mounting
Rear brake master cylinder and framePart to be tightened Thread size Q’tyTightening torque
Nm m•kg ft•lb
4
4
1
4
2
1
2
2
2
2
2
6
2
2
2
1
2
2
2
1
1
1
1
1
1
2
1
2
2
2
1
4
6
6
4
1
223
20
145
28
40
30
55
29
29
1
7
7
1
4
4
4
9
2
6
6
5
4
30
30
23
10
3
18
6
105
23
12
14
55
26
102.3
2.0
14.5
2.8
4.0
3.0
5.5
2.9
2.9
0.1
0.7
0.7
0.1
0.4
0.4
0.4
0.9
0.2
0.6
0.6
0.5
0.4
3.0
3.0
2.3
1.0
0.3
1.8
0.6
10.5
2.3
1.2
1.4
5.5
2.6
1.0
NOTE:
1. First, tighten the ring nut approximately 38 Nm (3.8 m•kg, 27 ft•lb) by using the ring nut wrench,
then loosen the ring nut one turn.
2. Retighten the ring nut 7 Nm (0.7 m•kg, 5.1 ft•lb).
Refer to NOTE.
1P8-9-31-2 5/19/05 10:30 AM Page 10

INSP
ADJ
3-2
MAINTENANCE INTERVALS
3
Item Remarks
COOLING SYSTEM
Check coolant level and leakage
Check radiator cap operation
Replace coolantEvery two years
Inspect hoses
OUTSIDE NUTS AND BOLTS Refer to “STARTING
RetightenAND BREAK-IN” section
in the CHAPTER 1.
AIR FILTER
Clean and lubricateUse foam air-filter oil or
Replaceequivalent oil
FRAME
Clean and inspect
FUEL TANK, COCK
Clean and inspect
BRAKES
Adjust lever position and pedal height
Lubricate pivot point
Check brake disc surface
Check fluid level and leakage
Retighten brake disc bolts, caliper bolts,

master cylinder bolts and union bolts
Replace pads
Replace brake fluidEvery one year
FRONT FORKS
Inspect and adjust
Replace oilSuspension oil “S1”
Replace oil seal
FRONT FORK OIL SEAL AND DUST SEAL
Clean and lubeLithium base grease
PROTECTOR GUIDE
Replace
REAR SHOCK ABSORBER
(After
Inspect and adjustrain ride)
Lube Molybdenum disulfide grease
Replace spring seatEvery one year
Retighten
CHAIN GUARD AND ROLLERS
Inspect
SWINGARM
Inspect, lube and retightenMolybdenum disulfide grease
RELAY ARM, CONNECTING ROD
Inspect, lube and retightenMolybdenum disulfide grease
STEERING HEAD
Inspect free play and retighten
Clean and lubeLithium base grease
Replace bearing
TIRE, WHEELS
Inspect air pressure, wheel run-out,

tire wear and spoke looseness
Retighten sprocket bolt
Inspect bearings
Replace bearings
LubricateLithium base grease
After
break-
inEvery
raceEvery
thirdEvery
fifthAs re-
quired
1P8-9-31-3A 5/13/05 11:42 AM Page 3

3-4
PRE-OPERATION INSPECTION AND MAINTENANCE
INSP
ADJ
EC320000
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation, practice or a race, make sure the machine is in good operating
condition.
Before using this machine, check the following points.
EC321000
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
Coolant Check that coolant is filled up to the radiator filler cap.
Check the cooling system for leakage.P3-5~9
Fuel Check that a fresh mixture of oil and gasoline is filled in
the fuel tank. Check the fuel line for leakage.P1-12
Transmission oil Check that the oil level is correct. Check the crankcase
for leakage.P3-12~14
Gear shifter and clutch Check that gears can be shifted correctly in order and
that the clutch operates smoothly.P3-9
Throttle grip/Housing Check that the throttle grip operation and free play
are correctly adjusted. Lubricate the throttle grip and P3-10~11
housing, if necessary.
Brakes Check the play of front brake and effect of front and
rear brake.P3-17~23
Chain Check chain slack and alignment. Check that the chain
is lubricated properly.P3-24~26
Wheels Check for excessive wear and tire pressure. Check for
loose spokes and have no excessive play.P3-34~35
Steering Check that the handlebar can be turned smoothly and
have no excessive play.P3-35~36
Front forks and Check that they operate smoothly and there is no oil
rear shock absorber leakage.P3-26~33
Cables (wires) Check that the clutch and throttle cables move smooth-
ly. Check that they are not caught when the handlebars —
are turned or when the front forks travel up and down.
Muffler Check that the muffler is tightly mounted and has no
cracks.P3-15~16
Sprocket Check that the driven sprocket tightening bolt is
not loose.P3-24
Lubrication Check for smooth operation. Lubricate if necessary. P3-37
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P1-16
Lead connectors Check that the CDI magneto, CDI unit, and ignition coil
are connected tightly.P1-6
Settings Is the machine set suitably for the condition of the
racing course and weather or by taking into account the
P7-1~23
results of test runs before racing? Are inspection and
maintenance completely done?
1P8-9-31-3A 5/13/05 11:42 AM Page 14