2001 YAMAHA YZ125LC ignition

CHAPTER 6
ELECTRICAL
ELECTRICAL COMPONENTS AND
WIRING DIAGRAM.....................................6-1
IGNITION SYSTEM.....................................6-2
CHAPTER 7
TUNING
ENGINE.......................................................7-1
CHASSIS...................................................7-13
5MV-9-30-0 6/19/00 2:05 PM Page 22

1-7
GEN
INFO
SPECIAL TOOLS
EC140001
SPECIAL TOOLS
The proper special tools are necessary for complete and accurate tune-up and assembly. Using the
correct special tool will help prevent damage caused by the use of improper tools or improvised tech-
niques. The shape and part number used for the special tool differ by country, so two types are provid-
ed. Refer to the list provided to avoid errors when placing an order.
NOTE:
9For U.S.A. and Canada, use part number starting with “YM-” or “YU-”.
9For others, use part number starting with “90890-”.
Part number Tool name / How to use IIIustration
YU-1135-A, 90890-01135Crankcase separating toolYU-1135-A 90890-01135
YM-1305, 90890-01305 Crankcase separating boltYM-1305 90890-01305
These tools are used to split the crankcase as well
as remove the crankshaft from either case.
YM-1189, 90890-01189 Flywheel puller
YM-1189 90890-01189
This tool is used to remove the flywheel magneto.
YU-1235, 90890-01235 Rotor holding tool
YU-1235 90890-01235
This tool is used when loosening or tightening the
flywheel magneto securing nut.
YU-3097, 90890-01252 Dial gauge and stand
YU-3097 90890-01252
YU-1256 StandYU-1256
These tools are used to set the ignition timing.
Crankcase installing tool
YU-90050 90890-01274
YU-90050, 90890-01274 PotYM-1277 90890-01275
YU-90050, 90890-01275 Bolt90890-01277
YM-1277, 90890-01277 Adapter
These tools are used to install the crankshaft.
YU-1304, 90890-01304 Piston pin puller
YU-1304 90890-01304
This tool is used to remove the piston pin.
YM-1312-A, 90890-01312Fuel level gaugeYM-1312-A 90890-01312
YM-01470, 90890-01470 Fuel level gauge adaptorYM-01470 90890-01470
This gauge is used to measure the fuel level in the
float chamber.
5MV-9-30-1A 6/19/00 1:11 PM Page 14

1-8
GEN
INFO
SPECIAL TOOLS
Part number Tool name / How to use IIIustration
YU-24460-01, 90890-01325Radiator cap testerYU-24460-01 90890-01325
YU-33984, 90890-01352 AdapterYU-33984 90890-01352
These tools are used for checking the cooling
system.
YU-33975, 90890-01403 Ring nut wrench
YU-33975 90890-01403
This tool is used when tighten the steering ring nut
to specification.
YM-1423, 90890-01423 Damper rod holder
YM-1423 90890-01423
Use this tool to remove and install the damper rod.
YM-01442, 90890-01442 Fork seal driver
YM-01442 90890-01442
This tool is used when install the fork oil seal.
YU-3112-C, Yamaha pocket tester
YU-3112-C 90890-03112
90890-03112
Use this tool to inspect the coil resistance,
output voltage and amperage.
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.
5MV-9-30-1A 6/19/00 1:12 PM Page 15

2-2
SPECGENERAL SPECIFICATIONS
Carburetor:
Type/Manufacturer TMXø
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 48/13 (3.692)
Transmission type Constant mesh, 6-speed
Operation Left foot operation
Gear ratio: 1st 30/13 (2.307)
2nd 28/15 (1.866)
3rd 26/17 (1.529)
4th 27/21 (1.285)
5th 26/23 (1.130)
6th 24/24 (1.000)
Chassis:USA, CDN, ZA, AUS, NZEUROPE
Frame type Semi double cradle¬
Caster angle 25.6° 25.4°
Trail 107 mm (4.21 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 kg/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
5MV-9-30-2A 6/19/00 1:15 PM Page 3

2-11
SPECMAINTENANCE SPECIFICATIONS
EC212300
ELECTRICAL
Part to be tightened Thread size Q’tyT ightening torqueNm m•kg ft•lb
Stator M 6 ´1.0 3 8 0.8 5.8
Rotor M10 ´1.25 1 33 3.3 24
Ignition coil M 6 ´1.0 2 7 0.7 5.1
Item Standard Limit
Ignition system:
Ignition timing (B.T.D.C.) 32°/3000 r/min…
0.52 mm (0.020 in)…
Advancer type Electrical…
CDI:
Magneto-model/Manufacturer F4SS00/YAMAHA…
Source coil 1 resistance (color) 720~1,080 ½at 20°C (68°F)…
(Green/White-Black/Red)
Source coil 2 resistance (color) 44~66 ½at 20°C (68°F)…
(Black-Green/Blue)
Pickup coil resistance (color) 248~372 ½at 20°C (68°F)…
(White/Blue-White/Red)
CDI unit-model/Manufacturer 5MV-00/YAMAHA…
Ignition coil:
Model/Manufacturer 4SS-00/YAMAHA…
Minimum spark gap 6 mm (0.24 in)…
Primary winding resistance 0.14~0.20 ½at 20°C (68°F)…
Secondary winding resistance 6.7~10.1k½at 20°C (68°F)…
5MV-9-30-2A 6/19/00 1:15 PM Page 12

2-14
SPECCABLE ROUTING DIAGRAM
1Brake hose holder
2Master cylinder
3Brake hose
4Hose guide
5CDI unit band
6CDI unit
7High tension cord
8Ignition coil
9Cable guide
0Radiator breather hose
qWireharness
w“ENGINE STOP” button lead
eCDI magneto lead
rClutch cable
tClamp
yCDI unit bracket
uEngine bracket
iCDI unit damper
APass the brake hose into
the brake hose holder.BIf the brake hose contacts
the spring (rear shock
absorber), correct its twist.
CInstall the brake hose so that
its pipe portion directs as
shown and lightly touches
the projection on the master
cylinder.
DPass the reservoir hose
between the brake hose and
swingarm bracket.
EPut the CDI unit fully in
the CDI unit band.
FFasten the ground lead
together with the ignition
coil.
GPass the cluch cable into
the cable guide.
HClamp the CDI magneto lead
on the upper part of
the frame gusset at its
protecting tube.IPass the clutch cable over
the radiator hose.
JClamp the wireharness on
the top of the CDI unit with
the clamp end downward.
KCut the clamp end to be flush
with CDI unit side.
LFit the CDI unit band over
the CDI unit bracket till it
stops.
MInstall the brake hose to
the caliper with the paint on
the pipe facing the caliper
and with the pipe contacting
the caliper projection.
NPass the radiator breather
hose between the frame and
radiator hose so that it is not
kinked or wedged.
OPosition the CDI unit between
the engine brackets as
shown.
5MV-9-30-2B 6/19/00 1:14 PM Page 28

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
P7-1~24
results of test runs before racing? Are inspection and
maintenance completely done?
5MV-9-30-3A 6/19/00 1:52 PM Page 14

3-39
IGNITION TIMING CHECK
INSP
ADJ
EC372051
IGNITION TIMING CHECK
1. Remove:
9Cylinder head
Refer to “CYLINDER HEAD, CYLINDER
AND PISTON” section in the CHAPTER 4.
9Crankcase cover (left)
2. Attach:
9Dial gauge 1
9Dial gauge stand 2
3. Rotate the magneto rotor 1until the
piston reaches top dead center (TDC).
When this happens, the needle on the dial
gauge will stop and reverse directions even
though the rotor is being turned in the same
direction.
4. Set the dial gauge to zero at TDC.
5. From TDC, rotate the rotor clockwise
until the dial gauge indicates that the
piston is at a specified distance from TDC.
6. Check:
9Ignition timing
Punch mark aon rotor should be aligned
with punch mark bon stator.
Not aligned ÕAdjust.
Dial gauge:
YU-3097/90890-01252
Stand:
YU-1256
Ignition timing (B.T.D.C.):
0.52 mm (0.020 in)
5MV-9-30-3B 6/19/00 1:50 PM Page 42