lock YAMAHA YZ125LC 2003 Owner's Guide

4-31
ENGCLUTCH AND PRIMARY DRIVEN GEAR
EC498100
PRIMARY DRIVEN GEAR
Extent of removal Order Part name Q’ty Remarks
PRIMARY DRIVEN GEAR
REMOVAL
1 Nut (clutch boss) 1
Use special tool.
2 Lock washer 1
Refer to “REMOVAL POINTS”.
3 Clutch boss 1
4
Plain washer [φ34 mm (1.34 in)] 1
5 Primary driven gear 1
6 Bearing 1
7
Plain washer [φ34 mm (1.34 in)]1
8 Push lever 1
Extent of removal:1Primary driven gear removal2Push lever removal
1
2





80 Nm (8.0 m•kg, 58 ft•lb)
7 Nm (0.7 m•kg, 5.1 ft•lb)
5UN-9-30-4B 1/7/04 4:36 PM Page 28

4-32
ENGCLUTCH AND PRIMARY DRIVEN GEAR
EC493000
REMOVAL POINTS
EC483211
Clutch boss
1. Remove:
9Nut 1
9Lock washer 2
9Clutch boss 3
NOTE:
Straighten the lock washer tab and use the
clutch holding tool 4, 5to hold the clutch boss.
å
For USA and CDN
∫
Except for USA and CDN
EC494000
INSPECTION
EC484100
Clutch housing and boss
1. Inspect:
9Clutch housing 1
Cracks/Wear/Damage  Replace.
9Clutch boss 2
Scoring/Wear/Damage Replace.
EC484201
Primary driven gear
1. Check:
9Circumferential play
Free play exists Replace.
9Gear teeth a
Wear/ Damage Replace.
EC484400
Clutch spring
1. Measure:
9Clutch spring free length a
Out of specification Replace springs as
a set.
Clutch holding tool:
YM-91042................................
4 4
90890-04086............................5 5
Clutch spring free length:
Standard
41.2 mm 39.2 mm
(1.622 in) (1.543 in)
å
∫å

4-34
ENGCLUTCH AND PRIMARY DRIVEN GEAR
EC495000
ASSEMBLY AND INSTALLATION
EC495240
Clutch
1. Install:
9Plain washer [
φ34 mm (1.34 in)] 1
9Spacer 2
9Bearing 3
9Primary driven gear 4
NOTE:
Apply the transmission oil on the spacer, bearing
and primary driven gear inner circumference.
2. Install:
9Plain washer [
φ34 mm (1.34 in)] 1
9Clutch boss 2
3. Install:
9Lock washer 1
9Nut (clutch boss) 2
NOTE:
Use the clutch holding tool 3, 4to hold the
clutch boss.
å
For USA and CDN
∫
Except for USA and CDN
4. Bend the lock washer 1tab.
80 Nm (8.0 m•kg, 58 ft•lb)
Clutch holding tool:
YM-91042...............................3 3
90890-04086...........................4 4
å
∫
5UN-9-30-4B 1/7/04 4:36 PM Page 34

4-44
ENG
KICK AXLE, SHIFT SHAFT AND PRIMARY DRIVE
GEAR
4. Hook:
9Torsion spring 1
NOTE:
Turn the torsion spring clockwise and hook into
the proper hole ain the crankcase.
EC4C5402
Kick idle gear
1. Install:
9Circlip 1
9Kick idle gear 2
9Plain washer 3
NOTE:
9Apply the transmission oil on the kick idle gear
inner circumference.
9Install the kick idle gear with its depressed side
atoward you.
EC4C5503
Primary drive gear
1. Install:
9Spacer 1
9Primary drive gear 2
9Bolt 3
NOTE:
Temporarily tighten the bolt at this point.
2. Install:
9Primary driven gear
Refer to “CLUTCH AND PRIMARY DRI-
VEN GEAR” section.
3. Tighten:
9Bolt (primary drive gear) 1
NOTE:
Place an aluminum plate abetween the teeth of
the primary drive gear 2and driven gear 3.
4. Install:
9Dowel pin 1
9Gasket [crankcase cover (right)] 2
55 Nm (5.5 m•kg, 40 ft•lb)

4-54
ENGCDI MAGNETO
EC4L3000
REMOVAL POINTS
EC4L3102
Rotor
1. Remove:
9Nut (rotor) 1
9Plain washer 2
Use the rotor holding tool 3.
2. Remove:
9Rotor 1
Use the flywheel puller 2.
NOTE:
When installing the flywheel puller, turn it coun-
terclockwise.
EC4L4000
INSPECTION
EC4L4101
CDI magneto
1. Inspect:
9Rotor inner surface a
9Stator outer surface b
Damage Inspect the crankshaft runout
and crankshaft bearing.
If necessary, replace CDI magneto and/or
stator.
EC4L4200
Woodruff key
1. Inspect:
9Woodruff key 1
Damage Replace.
EC4L5000
ASSEMBLY AND INSTALLATION
EC4L5172
CDI magneto
1. Install:
9Stator 1
9Screw (stator) 2
NOTE:
Temporarily tighten the screw (stator) at this
point.
Rotor holding tool:
YU-1235/90890-01235
Flywheel puller:
YM-1189/90890-01189

4-58
ENGENGINE REMOVAL
Extent of removal:1Engine removal
Extent of removal Order Part name Q’ty Remarks
1 Chain cover 1
2 Nut (drive sprocket) 1
3 Lock washer 1 Refer to “REMOVAL POINTS”.
4 Drive sprocket 1
5 Clip 1
6 Bolt (brake pedal) 1
7 Brake pedal 1
8 Engine bracket 2
9 Engine mounting bolt 3
10 Pivot shaft 1
Refer to “REMOVAL POINTS”.
11 Engine 1
1







26 Nm (2.6 m•kg, 19 ft•lb)
34 Nm (3.4 m•kg, 24 ft•lb)
69 Nm (6.9 m•kg, 50 ft•lb)
69 Nm (6.9 m•kg, 50 ft•lb)
85 Nm (8.5 m•kg, 61 ft•lb)
65 Nm (6.5 m•kg, 47 ft•lb)
5 Nm (0.5 m•kg, 3.6 ft•lb)

4-59
ENGENGINE REMOVAL
EC4M3000
REMOVAL POINTS
EC4F3100
Drive sprocket
1. Remove:
9Nut (drive sprocket) 1
9Lock washer 2
NOTE:
9Straighten the lock washer tab.
9Loosen the nut while applying the rear brake.
2. Remove:
9Drive sprocket 1
9Drive chain 2
NOTE:
Remove the drive sprocket together with the dri-
ve chain.
EC4M3301
Engine removal
1. Remove:
9Pivot shaft 1
NOTE:
If the pivot shaft is pulled all the way out, the
swingarm will come loose. If possible, insert a
shaft of similar diameter into the other side of
the swingarm to support it.
2. Remove:
9Engine 1
From right side.
NOTE:
Make sure that the couplers, hoses and cables
are disconnected.

4-61
ENGENGINE REMOVAL
2. Install:
9Lock washer 1
9Nut (drive sprocket) 2
NOTE:
Tighten the nut while applying the rear brake.
3. Bend the lock washer tab to lock the nut.
4. Install:
9Chain cover 1
9Screw (chain cover) 2
5 Nm (0.5 m•kg, 3.6 ft•lb)
65 Nm (6.5 m•kg, 47 ft•lb)

4-63
ENGCRANKCASE AND CRANKSHAFT
EC4N3000
REMOVAL POINTS
EC4N3100
Segment
1. Remove:
9Bolt (segment) 1
9Segment 2
NOTE:
Turn the segment counterclockwise until it stops
and loosen the bolt.
EC4N3212
Crankcase
1. Remove:
9Crankcase (right) 1
Use the crankcase separating tool 2.
NOTE:
9Make appropriate bolts 3as shown available
by yourself and attach the tool with them.
9Fully tighten the tool holding bolts, but make
sure the tool body is parallel with the case. If
necessary, one screw may be backed out
slightly to level tool body.
9As pressure is applied, alternately tap on the
front engine mounting boss and transmission
shafts.
cC
Use soft hammer to tap on the case half.
Tap only on reinforced portions of case. Do
not tap on gasket mating surface. Work
slowly and carefully. Make sure the case
halves separate evenly. If one end “hangs
up”, take pressure off the push screw, re-
align, and start over. If the cases do not
separate, check for a remaining case
screw or fitting. Do not force.
Crankcase separating tool:
YU-1135-A/90890-01135

4-68
ENGCRANKCASE AND CRANKSHAFT
6. Install:
9Holder 1
9Bolt (holder) 2
7. Install:
9Segment 1
9Bolt (segment) 2
NOTE:
9When installing the segment onto the shift cam
3, align the punch mark awith the dowel pin
b.
9Turn the segment clockwise until it stops and
tighten the bolt.
8. Remove:
9Sealant
Forced out on the cylinder mating surface.
9. Apply:
9Engine oil
To the crank pin, bearing, oil delivery hole
and connecting rod big end washer.
10. Check:
9Crankshaft and transmission operation
Unsmooth operation Repair.
30 Nm (3.0 m•kg, 22 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)