2004 YAMAHA YZ125LC ignition

CHAPTER 6
ELECTRICAL
ELECTRICAL COMPONENTS AND
WIRING DIAGRAM.....................................6-1
IGNITION SYSTEM.....................................6-2
CHAPTER 7
TUNING
ENGINE.......................................................7-1
CHASSIS...................................................7-14
5XE-9-30-0 3/24/03 11:08 PM Page 22

1-7
GEN
INFO
SPECIAL TOOLS
EC140002
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-”, “YU-” or “ACC-”.
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
These tool is 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 Spark plug hole dial standYU-1256
These tools are used to set the ignition timing.
Crankcase installing tool
YU-90050 90890-01274
YU-90050, 90890-01274 PotYU-90062 90890-01275
YU-90050, 90890-01275 Bolt90890-01277
YU-90062, 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.
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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-01442, 90890-01442 Fork seal driver
YM-01442 90890-01442
This tool is used when install the fork oil seal.
YM-01494, 90890-01494 Damper rod holder
YM-01494 90890-01494
Use this tool to remove and install the damper rod.
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.
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.
5XE-9-30-1A 4/16/03 10:22 AM Page 15

2-2
SPECGENERAL SPECIFICATIONS
Carburetor:
Type/Manufacturer TMXχ
38SS/MIKUNI
Spark plug:
Type/Manufacturer BR9EG/NGK (resistance type)
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 30/13 (2.308)
2nd 28/15 (1.867)
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
5XE-9-30-2A 5/10/03 1:57 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 9 0.9 6.5
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.) 0.52 mm (0.020 in)…
Advancer type Electrical…
CDI:
Magneto-model (stator)/Manufacturer 4SS-01/YAMAHA…
Source coil 1 resistance (color) 720~1,080 Ωat 20°C (68°F)…
(Green/White-Black/Red)
Source coil 2 resistance (color) 44~66 Ωat 20°C (68°F)…
(Black-Green/Blue)
Pickup coil resistance (color) 248~372 Ωat 20°C (68°F)…
(White/Blue-White/Red)
CDI unit-model/Manufacturer 5NY-11/YAMAHA…
Ignition coil:
Model/Manufacturer 5XE-00/YAMAHA…
Minimum spark gap 6 mm (0.24 in)…
Primary winding resistance 0.24~0.36 Ωat 20°C (68°F)…
Secondary winding resistance 5.7~8.5kΩat 20°C (68°F)…
Spark plug cap:
Resistance 4~6 kΩat 20°C (68°F)…
5XE-9-30-2A 5/10/03 1:57 PM Page 12

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
7Wireharness
8YPVS breather hose
9Radiator breather hose
0CDI magneto lead
q“ENGINE STOP” button lead
connector
wAir vent hose (left)
eOverflow hose
rAir vent hose (right)
tTransmission oil breather hoseAFasten the ground lead
together with the front
installation portion of the
ignition coil.
BPass 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.
CPass the fuel tank breather
hose between the handlebar
and tension bar, then insert
its end into the hole of the
number plate.
DPass the throttle cable and
“ENGINE STOP” button lead
over the radiator hose.
EClamp the throttle cable,
“ENGINE STOP” button lead
and wireharness to the main
pipe.FPass the wireharness on the
outside of the “ENGINE STOP”
button lead.
GClamp the throttle cable and
wireharness to the main pipe.
HPass the transmission oil
breather hose, air vent hoses
and overflow hose between
the frame and connecting rod.
IPass 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.
JClamp the radiator breather
hose and CDI magneto lead
on the rear of the down-tube.
5XE-9-30-2B 5/10/03 1:57 PM Page 26

2-15
SPECCABLE ROUTING DIAGRAM
1Cable guide
2Radiator breather hose
3Ignition coil
4CDI magneto lead
5Clutch cable
6CDI unit band
7CDI unit
8Wireharness
9High tension cord
0Clamp
qCDI unit bracketAPass the cluch cable into
the cable guide.
BInsert the ignition coil lead into
the ignition coil so that the lead
faces to the right of the frame.
CPass the clutch cable over
the radiator hose.
DPass the wireharness between
the convexites of the CDI unit
band.
EClamp the high tension cord on
the upper part of the frame
gusset at its protecting tube.
FPass the radiator breather hose
at the rear of the radiator hose
and in front of the ignition coil
bracket.GPush in the radiator hose until
its end lightly touches the radia-
tor pipe.
HCut the clamp end to be flush
with CDI unit side.
IFit the CDI unit band over
the CDI unit bracket till it
stops.
JClamp the wireharness on the
CDI unit with the clamp ends
upward.
5XE-9-30-2B 5/10/03 1:57 PM Page 30

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
P7-1~25
results of test runs before racing? Are inspection and
maintenance completely done?
5XE-9-30-3A 4/28/03 5:55 PM Page 14