2002 YAMAHA YZ426F ignition

CHAPTER 6
ELECTRICAL
ELECTRICAL COMPONENTS
AND WIRING DIAGRAM
.......................... 6-1
MAP-CONTROLLED CDI UNIT
................ 6-2
IGNITION SYSTEM
................................... 6-3
TPS (THROTTLE POSITION SENSOR)
SYSTEM
.................................................... 6-7
CHAPTER 7
TUNING
ENGINE
..................................................... 7-1
CHASSIS
................................................. 7-10

GEN
INFO
1 - 8
SPECIAL TOOLS
YU-33975, 90890-01403 Ring nut wrench
This tool is used when tighten the steering ring nut to
specification.YU-33975 90890-01403
YM-1423, 90890-01423 Damper rod holder
Use this tool to remove and install the damper rod.YM-1423 90890-01423
YM-01442, 90890-01442 Fork seal driver
This tool is used when install the fork oil seal.YM-01442 90890-01442
YU-3112-C, 90890-03112 Yamaha pocket tester
Use this tool to inspect the coil resistance, output
voltage and amperage.YU-3112-C 90890-03112
YU-8036-B,
90890-03113Inductive tachometer
Engine tachometer
This tool is needed for observing engine rpm.YU-8036-B 90890-03113
YM-33277-A, 90890-03141 Timing light
This tool is necessary for checking ignition timing.YM-33277-A 90890-03141
YM-4019, 90890-04019 Valve spring compressor
This tool is needed to remove and install the valve
assemblies.YM-4019 90890-04019
YM-91042, 90890-04086 Clutch holding tool
This tool is used to hold the clutch when removing or
installing the clutch boss securing nut.YM-91042 90890-04086
YM-4116, 90890-04116
YM-4097, 90890-04097Valve guide remover
Intake (4.5 mm)
Exhaust (5.0 mm)
This tool is needed to remove and install the valve
guide.YM-4116
YM-409790890-04116
90890-04097
Part number Tool name/How to use Illustration

GEN
INFO
1 - 9
SPECIAL TOOLS
YM-4117, 90890-04117
YM-4098, 90890-04098Valve guide installer
Intake
Exhaust
This tool is needed to install the valve guide.YM-4117
YM-409890890-04117
90890-04098
YM-4118, 90890-04118
YM-4099, 90890-04099Valve guide reamer
Intake (4.5 mm)
Exhaust (5.0 mm)
This tool is needed to rebore the new valve guide.YM-4118
YM-409990890-04118
90890-04099
YM-34487
90890-06754Dynamic spark tester
Ignition checker
This instrument is necessary for checking the ignition
system components.YM-34487 90890-06754
ACC-QUICK-GS-KT
90890-85505Quick gasket

YAMAHA Bond No. 1215
This sealant (Bond) is used for crankcase mating
surface, etc.ACC-QUICK-GS-KT 90890-85505
Part number Tool name/How to use Illustration

SPEC

2 - 3
GENERAL SPECIFICATIONS
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

SPEC
2 - 17
MAINTENANCE SPECIFICATIONS
EC212300
ELECTRICAL
Item Standard Limit
Ignition system:
Advancer type Electrical ----
C.D.I.:
Magneto-model (stator)/manufacturer 5SF-00/YAMAHA ----
Source coil 1 resistance (color) 720 ~ 1,080 Ω at 20 ˚C (68 ˚F)
(Green – Brown)----
Source coil 2 resistance (color) 44 ~ 66 Ω at 20 ˚C (68 ˚F)
(Black – Pink)----
Pickup coil resistance (color) 248 ~ 372 Ω at 20 ˚C (68 ˚F)
(White – Red)----
CDI unit-model/manufacturer 5SF-00/YAMAHA ----
Ignition coil:
Model/manufacturer 5BE-00/YAMAHA ----
Minimum spark gap 6 mm (0.24 in) ----
Primary winding resistance 0.20 ~ 0.30 Ω at 20 ˚C (68 ˚F) ----
Secondary winding resistance 9.5 ~ 14.3 kΩ at 20 ˚C (68 ˚F) ----
Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Stator M6 × 1.0 3 10 1.0 7.2
Rotor M10 × 1.25 1 48 4.8 35
Ignition coil M6 × 1.0 2 7 0.7 5.1

2 - 23
SPEC
„Pass the neutral switch lead and
CDI magneto lead through the
cable guide and over the middle
radiator mounting boss. Then, pass
the decompression cable under the
middle radiator mounting boss and
along the left side of the neutral
switch lead and CDI magneto lead.
ÙFit the brake hose into the guides
on the protector.
ÁFasten the ignition coil lead (in the
sub wire harness) on the upper
inside of the frame and cut off the
tie end.
ÛPass the ignition coil lead (in the
sub wire harness) under the cush-
ion bracket (frame).Fasten the ignition coil lead (in the
sub wire harness) to the frame
and cut off the tie end.
Pass the carburetor breather
hoses and overflow hose so that
all there hoses do not contact the
rear shock absorber.AA
AB
CABLE ROUTING DIAGRAM

2 - 24
SPECCABLE ROUTING DIAGRAM
1Clamp
2Ignition coil
3High tension cord
4CDI unit
5CDI unit band
6“ENGINE STOP” button
lead
7Throttle cable (pull)
8Throttle cable (return)
9Radiator (left)
0Radiator breather hose
ARadiator (right)
BCDI unit stay (frame)ÅFasten the ignition coil lead to the
frame with a plastic band.
ıFasten the ignition coil and ground
lead to the frame with the bolt.
ÇPass the ignition coil lead (in the
sub wire harness) so that it does
not contact the carburetor and
rear shock absorber and connect
it with the lead from the ignition
coil on the inside of the frame.
ÎPass the throttle cables over the
high tension cord.
‰Pass the throttle cables along the
outer side of the CDI unit leads.
ÏFasten the CDI unit leads and
“ENGINE STOP” button lead to the
frame at the protector of the CDI
unit leads with a plastic locking tie.
ÌPass the radiator breather hose
on the outside the CDI unit lead
and “ENGINE STOP” button lead.ÓPass the CDI unit lead and
“ENGINE STOP” button lead over
the top radiator mounting boss.
ÈPass the throttle cables and
“ENGINE STOP” button lead
through the cable guide.
ÔCross the pull and return throttle
cables before the radiator.
Pass the throttle cables, “ENGINE
STOP” button lead and CDI unit
lead through the cable guide.
ÒPass the throttle cables between
the top radiator mounting boss and
middle radiator mounting boss.
˜Pass the radiator breather hose
between the frame and the radia-
tor without pinching it.
ˆPass the radiator breather hose
behind the decompression cable.
ØInsert the CDI unit band over the
CDI unit stay (frame) as far as
possible.

3 - 4
INSP
ADJ
PRE-OPERATION INSPECTION AND MAINTENANCE
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.
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
CoolantCheck that coolant is filled up to the radiator filler cap.
Check the cooling system for leakage.P.3-5 ~ 9
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the
fuel line for leakage.P.1-14
Engine oilCheck that the oil level is correct. Check the crankcase and
frame oil line for leakage.P.3-13 ~ 17
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-9
Throttle grip/HousingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-10 ~ 11
Brakes Check the play of front brake and effect of front and rear brake. P.3-24 ~ 30
ChainCheck chain slack and alignment. Check that the chain is lubri-
cated properly.P.3-31 ~ 33
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-41 ~ 42
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-42 ~ 43
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage. P.3-33 ~ 40
Cables (wires)Check that the clutch and throttle cables move smoothly. 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.—
Sprocket Check that the driven sprocket tightening bolt is not loose. P.3-31
Lubrication Check for smooth operation. Lubricate if necessary. P.3-44
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-19
Lead connectorsCheck that the CDI magneto, CDI unit, and ignition coil are con-
nected tightly.P.1-6
SettingsIs the machine set suitably for the condition of the racing course
and weather or by taking into account the results of test runs
before racing? Are inspection and maintenance completely
done?P.7-1 ~ 21