2001 YAMAHA YZ125LC fuel

4-7
ENGCARBURETOR AND REED VALVE
EC460000
CARBURETOR AND REED VALVE
Extent of removal Order Part name Q’ty Remarks
CARBURETOR AND
REED VALVE REMOVAL
Preparation for Fuel tank Refer to “SEAT, FUEL TANK AND
removal SIDE COVERS” section.
1 Clamp (carburetor joint) 2
Loosen the screws (carburetor joint).
2 Carburetor 1
3 Carburetor joint 1
4 Reed valve assembly 1
5 Stopper (reed valve) 2
6 Reed valve 21
Extent of removal:1Carburetor removal2Reed valve removal
2
10 Nm (1.0 m•kg, 7.2 ft•lb)
1 Nm (0.1 m•kg, 0.7 ft•lb)
5MV-9-30-4A 6/19/00 1:47 PM Page 14

4-11
ENGCARBURETOR AND REED VALVE
Measurement and adjustment steps:
9Remove the drain plug.
9Connect the fuel level gauge adapter 2and
fuel level gauge 1to the float chamber.
Fuel level gauge adapter:
YM-01470/90890-01470
Fuel level gauge:
YM-1312-A/90890-01312
9Hold the fuel level gauge vertically next to
the float chamber mating surface.
9Measure the fuel level with the fuel level
gauge.
NOTE:
Keep the carburetor and fuel level gauge ver-
tically when measuring the fuel level.
9If the fuel level is not within specification, in-
spect the valve seat and needle valve.
9If either is worn, replace them both.
9If both are fine, adjust the fuel level by bend-
ing the float tab bon the float.
9Recheck the fuel level.
EC464802
Fuel level
1. Measure:
9Fuel level a
Out of specification ÕAdjust.
Fuel level:
13.5~14.5 mm (0.53~0.57 in)
Above the float chamber
mating surface
EC464A00
Filter
1. Inspect:
9Filter 1
Damage Õ Replace.
NOTE:
Inspect the filter as it is assembled to the carbu-
retor. Do not remove the filter except when
replacing it.
5MV-9-30-4A 6/19/00 1:47 PM Page 22

4-17
ENGCYLINDER HEAD, CYLINDER AND PISTON
EC470000
CYLINDER HEAD, CYLINDER AND PISTONEC478000
CYLINDER HEAD AND CYLINDER
Extent of removal Order Part name Q’ty Remarks
CYLINDER HEAD AND
CYLINDER REMOVAL
Preparation for Seat and fuel tank Refer to “SEAT, FUEL TANK AND
removal SIDE COVERS” section.
Exhaust pipe and silencer Refer to ”EXHAUST PIPE AND
SILENCER” section.
Radiator hose 2 Disconnect at cylinder head side.
Bolt (radiator) Refer to “RADIATOR” section.
Radiator hose 3 Disconnect at right side radiator,
then shift the radiators forward.
1 Spark plug 1
2 Engine bracket 2
3 Nut (cylinder head) 5
Loosen each nut 1/4 turn, and remove
them after all nuts are loosened.
4 Cylinder head 1
5 Power valve housing 1
6 Push rod 1 Refer to “REMOVAL POINTS”.
7 Nut (cylinder) 4
8 Cylinder 1
Extent of removal:1Cylinder head removal2Cylinder removal
1
2
34 Nm (3.4 m•kg, 24 ft•lb)
20 Nm (2.0 m•kg, 14 ft•lb)
28 Nm (2.8 m•kg, 20 ft•lb)
5 Nm (0.5 m•kg, 3.6 ft•lb)
5 Nm (0.5 m•kg, 3.6 ft•lb)
30 Nm (3.0 m•kg, 22 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
5MV-9-30-4A 6/19/00 1:47 PM Page 34

4-53
ENGCDI MAGNETO
Extent of removal Order Part name Q’ty Remarks
CDI MAGNETO REMOVAL
Preparation for Seat and fuel tank Refer to “SEAT, FUEL TANK AND
removal SIDE COVERS” section.
Bolt [Radiator (left)] Refer to “RADIATOR” section.
Disconnect the CDI magneto lead.
1 Crankcase cover (left) 1
2 Nut (rotor) 1 Use special tool.
3 Rotor 1 Refer to “REMOVAL POINTS”.
4 Stator 1
5 Woodruff key 1
EC4L0000
CDI MAGNETO
1
Extent of removal:1CDI magneto removal
ü
ý
þ
8 Nm (0.8 m•kg, 5.8 ft•lb)
33 Nm (3.3 m•kg, 24 ft•lb)
5 Nm (0.5 m•kg, 3.6 ft•lb)
5MV-9-30-4C 6/19/00 1:42 PM Page 32

4-57
ENGENGINE REMOVAL
Extent of removal Order Part name Q’ty Remarks
ENGINE REMOVAL
Preparation for
Hold the machine by placing the
removalsuitable stand under the engine.
Seat and fuel tankRefer to “SEAT, FUEL TANK AND
SIDE COVERS” section.
Carburetor Refer to “CARBURETOR AND REED
VALVE” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
Clutch cable Disconnect at engine side.
Radiator hose 2 Disconnect at cylinder head side.
Radiator hose 4 Disconnect at water pump side.
Bolt (radiator) Refer to “RADIATOR” section.
Radiator hose 3 Disconnect at right side radiator,
then shift the radiators forward.
Spark plug cap
Disconnect the CDI magneto lead.
EC4M0000
w
Support the machine securely so there is no dan-
ger of it falling over.
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)
60 Nm (6.0 m•kg, 43 ft•lb)
5 Nm (0.5 m•kg, 3.6 ft•lb)
5MV-9-30-4D 6/19/00 1:39 PM Page 2

5-46
CHASHANDLEBAR
14. Clamp the clamp portion aof the number
plate to the handlebar.
15. Insert the end of the fuel breather hose 1
into the hole of the number plate.
5MV-9-30-5C 6/19/00 1:27 PM Page 14

5-59
CHASREAR SHOCK ABSORBER
EC580000
Extent of removal Order Part name Q’ty Remarks
REAR SHOCK ABSORBER
REMOVAL
Preparation forHold the machine by placing the
removalsuitable stand under the engine.
SeatRefer to “SEAT, FUEL TANK AND
SIDE COVERS” section.
SilencerRefer to “EXHAUST PIPE AND
SILENCER” section.
1 Clamp (air cleaner joint) 1 Loosen the screw (air cleaner joint).
2 Rear frame 1
3
Bolt (rear shock absorber-relay arm)1 Hold the swingarm.
4 Bolt (rear shock absorber-frame) 1
5 Rear shock absorber 1
6 Locknut 1
7 Adjuster 1
8 Spring guide (lower) 1
9 Spring guide (upper) 1
10 Spring (rear shock absorber) 1
11 Bearing 2 Refer to “REMOVAL POINTS”.
2
w
Support the machine securely so there is no dan-
ger of it falling over.
Extent of removal:1Rear shock absorber removal 2Rear shock absorber disassembly
1
56 Nm (5.6 m•kg, 40 ft•lb)
53 Nm (5.3 m•kg, 38 ft•lb)
29 Nm (2.9 m•kg, 21 ft•lb)
5MV-9-30-5D 6/19/00 1:26 PM Page 16

6-2
ELECIGNITION SYSTEM
EC620000
IGNITION SYSTEM
EC621002
INSPECTION STEPS
Use the following steps for checking the possibility of the malfunctioning engine being attributable to
ignition system failure and for checking the spark plug which will not spark.
*Clean or replace
spark plug.
Primary coil
Secondary coil
Repair or replace.
Spark
Check entire ignition
system for connection.
Spark gap test
No good
No good
No good
No good
No good
No good No Spark
Check “ENGINE STOP”
button.
Pick-up coil
Source coil
Check ignition coil.
Check CDI magneto.
Replace CDI unit.
Replace.
Replace.
Replace.
Replace.
Replace.
*marked: Only when the ignition checker is used.
NOTE:
9Remove the following parts before inspection.
1) Seat
2) Fuel tank
9Use the following special tools in this inspection.
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754Pocket tester:
YU-3112-C/90890-03112
OK
OK
OK
OK
5MV-9-30-6 6/19/00 1:25 PM Page 4