brake YAMAHA YZ125LC 2002 Owners Manual

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.....................................................4-17
CLUTCH AND PRIMARY DRIVEN
GEAR.......................................................4-30
KICK AXLE, SHIFT SHAFT AND
PRIMARY DRIVE GEAR...........................4-38
YPVS GOVERNOR...................................4-46
WATER PUMP..........................................4-49
CDI MAGNETO.........................................4-53
ENGINE REMOVAL..................................4-57
CRANKCASE AND CRANKSHAFT.........4-62
TRANSMISSION, SHIFT CAM AND
SHIFT FORK.............................................4-69
CHAPTER 5
CHASSIS
FRONT WHEEL AND REAR WHEEL........5-1
FRONT BRAKE AND REAR BRAKE.......5-10
FRONT FORK...........................................5-27
HANDLEBAR............................................5-40
STEERING................................................5-47
SWINGARM..............................................5-52
REAR SHOCK ABSORBER.....................5-59
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1-1
GEN
INFO
DESCRIPTION
EC100000
GENERAL INFORMATION
EC110000
DESCRIPTION
1Clutch lever
2”ENGINE STOP” button
3Front brake lever
4Throttle grip
5Radiator cap
6Fuel tank cap
7Kick starter
8Fuel tank
9Radiator
0Coolant drain bolt
qCheck bolt (Transmission oil level)
wRear brake pedal
eValve joint
rFuel cock
tAir cleaner
yDrive chain
uShift pedal
iStarter knob
oFront fork
NOTE:
9The machine you have purchased may differ
slightly from those shown in the following.
9Designs and specifications are subject to
change without notice.
1
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1-10
GEN
INFO
CONTROL FUNCTIONS
EC156000
FRONT BRAKE LEVER
The front brake lever 1is located on the right
handlebar. Pull it toward the handlebar to acti-
vate the front brake.
EC157000
REAR BRAKE PEDAL
The rear brake pedal 1is located on the right
side of the machine. Press down on the brake
pedal to activate the rear brake.
EC158001
FUEL COCK
The fuel cock supplies fuel from the tank to car-
buretor while filtering the fuel. The fuel cock has
the two positions:
OFF: With the lever in this position, fuel will not
flow. Always return the lever to this posi-
tion when the engine is not running.
ON: With the lever in this position, fuel flows to
the carburetor. Normal riding is done with
the lever in this position.
EC159000
STARTER KNOB (CHOKE)
When cold, the engine requires a richer air-fuel
mixture for starting. A separate starter circuit,
which is controlled by the starter knob 1, sup-
plies this mixture. Pull the starter knob out to
open the circuit for starting. When the engine
has warmed up, push it in to close the circuit.
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1-16
GEN
INFO
TORQUE-CHECK POINTS
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
Rear Brake pedal to frame
Brake disc to wheel
Tighening of union bolt
Master cylinder to frame
Tightening of air bleeder
Fuel system Fuel tank to fuel cock
NOTE:
Concerning the tightening torque, refer to “
MAINTENANCE SPECIFICATIONS” section in
the CHAPTER 2.
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1-17
GEN
INFO
CLEANING AND STORAGE
EC1B0000
CLEANING AND STORAGE
EC1B1000
CLEANING
Frequent cleaning of your machine will enhance
its appearance, maintain good overall perfor-
mance, and extend the life of many components.
1. Before washing the machine, block off the
end of the exhaust pipe to prevent water
from entering. A plastic bag secured with a
rubber band may be used for this purpose.
2. If the engine is excessively greasy, apply
some degreaser to it with a paint brush. Do
not apply degreaser to the chain, sprockets,
or wheel axles.
3. Rinse the dirt and degreaser off with a gar-
den hose; use only enough pressure to do
the job.
cC
Excessive hose pressure may cause water
seepage and contamination of wheel bear-
ings, front forks, brakes and transmission
seals. Many expensive repair bills have re-
sulted from improper high pressure deter-
gent applications such as those available
in coin-operated car washers.
4. After the majority of the dirt has been hosed
off, wash all surfaces with warm water and a
mild detergent. Use an old toothbrush to
clean hard-to-reach places.
5. Rinse the machine off immediately with
clean water, and dry all surfaces with a soft
towel or cloth.
6. Immediately after washing, remove excess
water from the chain with a paper towel and
lubricate the chain to prevent rust.
7. Clean the seat with a vinyl upholstery clean-
er to keep the cover pliable and glossy.
8. Automotive wax may be applied to all paint-
ed or chromed surfaces. Avoid combination
cleaner-waxes, as they may contain abra-
sives.
9. After completing the above, start the engine
and allow it to idle for several minutes.
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2-2
SPECGENERAL SPECIFICATIONS
Carburetor:
Type/Manufacturer TMXχ
38SS/MIKUNI
Spark plug:
Type/Manufacturer BR9EG/NGK
Gap 0.5~0.6 mm (0.020~0.024 in)
Clutch type: Wet, multiple-disc
Transmission:
Primary reduction system Gear
Primary reduction ratio 64/19 (3.368)
Secondary reduction system Chain drive
Secondary reduction ratio 49/13 (3.769)
Transmission type Constant mesh, 5-speed
Operation Left foot operation
Gear ratio: 1st 27/12 (2.250)
2nd 31/17 (1.824)
3rd 29/19 (1.526)
4th 24/19 (1.263)
5th 25/23 (1.087)
Chassis:USA, ZA, AUS, NZEUROPE,CDN
Frame type Semi double cradle←
Caster angle 25.6° 25.4°
Trail 108 mm (4.25 in) 104 mm (4.09 in)
Tire:
Type With tube
Size (front) 80/100-21 51M
Size (rear) 100/90-19 57M
Tire pressure (front and rear) 100 kPa (1.0 kgf/cm2, 15 psi)
Brake:
Front brake type Single disc brake
Operation Right hand operation
Rear brake type Single disc brake
Operation Right foot operation
Suspension:
Front suspension Telescopic fork
Rear suspension Swingarm (link type monocross suspension)
Shock absorber:
Front shock absorber Coil spring/oil damper
Rear shock absorber Coil spring/Gas, oil damper
Wheel travel:
Front wheel travel 300 mm (11.8 in)
Rear wheel travel 315 mm (12.4 in)
Electrical:
Ignition system CDI magneto
2
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2-8
SPECMAINTENANCE SPECIFICATIONS
Item Standard Limit
Wheel:
Front wheel type Spoke wheel…
Rear wheel type Spoke wheel…
Front rim size/Material 21 ×1.60/Aluminum…
Rear rim size/Material 19 ×1.85/Aluminum…
Rim runout limit:
Radial…
2.0 mm (0.08 in)
Lateral … 2.0 mm (0.08 in)
Drive chain:
Type/Manufacturer DID520DMA2 SDH/DAIDO …
Number of links 111 links+joint …
Chain slack 40~50 mm (1.6~2.0 in) …
Chain length (10 links) … 152.5 mm (6.004 in)
Front disc brake:
Disc outside dia. ×Thickness 250 ×3.0 mm (9.84 ×0.12 in)…
Pad thickness 4.4 mm (0.17 in) 1.0 mm (0.04 in)
Master cylinder inside dia. 11.0 mm (0.433 in)…
Caliper cylinder inside dia. 27.0 mm (1.063 in) ×2…
Brake fluid type DOT #4…
Rear disc brake:
Disc outside dia. ×Thickness 245 ×4.0 mm (9.65 ×0.16 in)…
Deflection limit…
0.15 mm (0.006 in)
Pad thickness 6.4 mm (0.25 in) 1.0 mm (0.04 in)
Master cylinder inside dia. 12.7 mm (0.500 in)…
Caliper cylinder insdie dia. 27.0 mm (1.063 in)…
Brake fluid type DOT #4…
Brake lever & brake pedal:
Brake lever position 95 mm (3.74 in)…
Brake pedal height Zero mm (Zero in)…
(vertical height above footrest top)
Clutch lever free play (lever end) 8~13 mm (0.31~0.51 in)…
Throttle grip free play 3~5 mm (0.12~0.20 in)…
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2-9
SPECMAINTENANCE SPECIFICATIONS
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).
Part to be tightened Thread size Q'tyT ightening torqueNm m•kg ft•lb
Handle crown and outer tube M 8 ×1.25 4 23 2.3 17
Under bracket and outer tube M 8 ×1.25 4 20 2.0 14
Handle crown and steering shaft M24 ×1.0 1 145 14.5 105
Handlebar holder (upper) M 8 ×1.25 4 28 2.8 20
Steering ring nut M28 ×1.0 1 Refer to NOTE
Front fork and cap bolt M48 ×1.0 2 30 3.0 22
Front fork and base valve M30 ×1.0 2 55 5.5 40
Cap bolt and damper rod (front fork) M12 ×1.25 2 29 2.9 21
Bleed screw (front fork) and cap bolt M 5 ×0.8 2 1 0.1 0.7
Front fork and protector M 6 ×1.0 6 10 1.0 7.2
Cable guide (front brake hose) and guide stayM 5 ×0.8 1 4 0.4 2.9
Front fork and brake hose holder M 6 ×1.0 2 10 1.0 7.2
Front fork and hose cover M 8 ×1.25 1 16 1.6 11
Front fork and hose cover M 6 ×1.0 1 7 0.7 5.1
Throttle cable cap M 4 ×0.7 2 1 0.1 0.7
Front brake master cylinder and bracket M 6 × 1.0 2 9 0.9 6.5
Brake lever (bolt) M 6 ×1.0 1 6 0.6 4.3
(nut) M 6 ×1.0 1 6 0.6 4.3
Brake lever position locknut M 6 ×1.0 1 5 0.5 3.6
Clutch lever (bolt) M 6 ×1.0 1 2 0.2 1.4
Clutch lever holder M 5 ×0.8 2 4 0.4 2.9
Front brake master cylinder cap M 4 ×0.7 2 2 0.2 1.4
Front brake hose union bolt (master cylinder)M10 ×1.25 1 30 3.0 22
Front brake hose union bolt (caliper) M10 ×1.25 1 30 3.0 22
Front brake caliper and front fork M 8 ×1.25 2 23 2.3 17
Grip cap upper and lower M 6 ×1.0 2 4 0.4 2.9
Brake caliper (front and rear) and pad pin plugM10 ×1.0 1 3 0.3 2.2
Brake caliper (front and rear) and pad pin M10 ×1.0 1 18 1.8 13
Brake caliper (front and rear) and bleed screwM 8 ×1.25 1 6 0.6 4.3
Front wheel axle and nut M16 ×1.5 1 105 10.5 75
Front wheel axle holder M 8 ×1.25 4 23 2.3 17
Front brake disc and wheel hub M 6 ×1.0 6 12 1.2 8.7
Rear brake disc and wheel hub M 6 ×1.0 6 14 1.4 10
Brake pedal mounting M 8 ×1.25 1 26 2.6 19
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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2-10
SPECMAINTENANCE SPECIFICATIONS
Part to be tightened Thread size Q'tyT ightening torqueNm m•kg ft•lb
Rear brake master cylinder and frame M 6 ×1.0 2 10 1.0 7.2
Rear brake reservoir tank and frame M 6 ×1.0 1 7 0.7 5.1
Rear brake hose union bolt (caliper) M10 ×1.25 1 30 3.0 22
Rear brake hose union bolt (master cylinder) M10 ×1.25 1 30 3.0 22
Rear wheel axle and nut M20 ×1.5 1 125 12.5 90
Nipple (spoke) – 72 3 0.3 2.2
Driven sprocket and wheel hub M 8 ×1.25 6 42 4.2 30
Disc cover and rear brake caliper M 6 ×1.0 2 7 0.7 5.1
Protector and rear brake caliper M 6 ×1.0 2 7 0.7 5.1
Engine mounting:
Engine and frame (front) M10 ×1.25 1 69 6.9 50
Engine and frame (lower) M10 ×1.25 1 69 6.9 50
Engine bracket and frame M 8 ×1.25 2 34 3.4 24
Engine bracket and engine M 8 ×1.25 1 34 3.4 24
Pivot shaft and nut M16 ×1.5 1 85 8.5 61
Relay arm and swingarm M14 ×1.5 1 80 8.0 58
Relay arm and connecting rod M14 ×1.5 1 80 8.0 58
Connecting rod and frame M14 ×1.5 1 80 8.0 58
Rear shock absorber and frame M10 ×1.25 1 56 5.6 40
Rear shock absorber and relay arm M10 ×1.25 1 53 5.3 38
Rear frame and frame M 8 ×1.25 3 29 2.9 21
Swingarm and brake hose holder M 5 ×0.8 4 2 0.2 1.4
Chain tensioner mounting M 8 ×1.25 2 19 1.9 13
Chain support and swingarm M 6 ×1.0 3 7 0.7 5.1
Seal guard and swingarm M 5 ×0.8 4 6 0.6 4.3
Fuel tank mounting M 6 ×1.0 2 10 1.0 7.2
Fuel tank and fuel cock M 6 ×1.0 2 7 0.7 5.1
Fuel tank and seat set bracket M 6 ×1.0 1 7 0.7 5.1
Fuel tank and hooking screw (fitting band) M 6 ×1.0 1 7 0.7 5.1
Fuel tank and fuel tank bracket M 6 ×1.0 4 7 0.7 5.1
Air scoop mounting M 6 ×1.0 6 4 0.4 2.9
Front fender mounting M 6 ×1.0 4 7 0.7 5.1
Rear fender mounting M 6 ×1.0 4 7 0.7 5.1
Side cover mounting M 6 ×1.0 2 7 0.7 5.1
Seat mounting M 8 ×1.25 2 19 1.9 13
Number plate M 6 ×1.0 1 7 0.7 5.1
NOTE:

- marked portion shall be checked for torque tightening after break-in or before each race.


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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2-13
SPECCABLE ROUTING DIAGRAM
EC240000
CABLE ROUTING DIAGRAM
1Brake hose
2Cable guide
3“ENGINE STOP” button lead
4Fuel tank breather hose
5Clamp
6Throttle cable
7Air vent hose (right)
8Air vent hose (left)
9Transmission oil breather hose
0Overflow hose
qYPVS breather hose
wRadiator breather hose
eCDI magneto lead
rWireharnessAPass the throttle cable and
“ENGINE STOP” button lead
into the cable guide. Align
with the cable guide the
front end of the tape on the
throttle cable.
BPass the fuel tank breather
hose between the handlebar
and tension bar, then insert
its end into the hole of the
number plate.
CPass the throttle cable and
“ENGINE STOP” button lead
over the radiator hose.
DClamp the throttle cable,
“ENGINE STOP” button lead
and wireharness to the main
pipe. With the clamp ends
downward, tighten the throttle
cable to the extent that it
moves smoothly.
EClamp the “ENGINE STOP”
button lead (where there is no
protector), wireharness and
throttle cable all together to the
main pipe with the clamp ends
downward.FClamp the CDI magneto lead
on the upper part of
the frame gusset at its
protecting tube.
GClamp the throttle cable and
wireharness to the main pipe.
With the clamp ends downward,
tighten the throttle cable to the
extent that it moves smoothly.
HPass the air vent hose at
the rear of the throttle cable.
IPass the transmission oil
breather hose, air vent hoses
and overflow hose between
the frame and connecting rod.
JPass the radiator breather
hose and YPVS breather hose
outside the engine bracket
and inside the down tube. Then
pass the radiator breather
hose inside the YPVS
breather hose.
KClamp the radiator breather
hose and CDI magneto lead
on the rear of the down-tube.
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