FOREWORD
INTRODUCTION
Congratulations on your purchase of
a Yamaha YZ series. This model is
the culmination of Yamaha's vast ex-
perience in the production of paceset-
ting racing machines. It represents
the highest grade of craftsmanship
and reliability that have made Yama-
ha a leader.
This manual explains operation, in-
spection, basic maintenance and tun-
ing of your machine. If you have any
questions about this manual or your
machine, please contact your Yama-
ha dealer.
Yamaha continually seeks advance-
ments in product design and quality.
Therefore, while this manual contains
the most current product information
available at the time of printing, there
may be minor discrepancies between
your machine and this manual. If you
have any questions concerning this
manual, please consult your Yamaha
dealer.
PLEASE READ THIS MANUAL
CAREFULLY AND COMPLETELY
BEFORE OPERATING THIS MA-
CHINE. DO NOT ATTEMPT TO OP-
ERATE THIS MACHINE UNTIL YOU
HAVE ATTAINED A SATISFACTO-
RY KNOWLEDGE OF ITS CON-
TROLS AND OPERATING
FEATURES AND UNTIL YOU HAVE
BEEN TRAINED IN SAFE AND
PROPER RIDING TECHNIQUES.
REGULAR INSPECTIONS AND
CAREFUL MAINTENANCE,
ALONG WITH GOOD RIDING
SKILLS, WILL ENSURE THAT YOU
SAFETY ENJOY THE CAPABILI-
TIES AND THE RELIABILITY OF
THIS MACHINE.
IMPORTANT MANUAL
INFORMATION
Particularly important information is
distinguished in this manual by the
following notations.
This is the safety alert symbol. It is
used to alert you to potential per-
sonal injury hazards. Obey all safe-
ty messages that follow this
symbol to avoid possible injury or
death.
A WARNING indicates a hazardous
situation which, if not avoided,
could result in death or serious in-
jury.
A NOTICE indicates special pre-
cautions that must be taken to
avoid damage to the vehicle or oth-
er property.
A TIP provides key information to
make procedures easier or clearer.
SAFETY INFORMATION
THIS MACHINE IS DESIGNED
STRICTLY FOR COMPETITION
USE, ONLY ON A CLOSED
COURSE. It is illegal for this machine
to be operated on any public street,
road, or highway. Off-road use on
public lands may also be illegal.
Please check local regulations before
riding.
• THIS MACHINE IS TO BE OPER-
ATED BY AN EXPERIENCED RID-
ER ONLY.
Do not attempt to operate this ma-
chine at maximum power until you
are totally familiar with its character-
istics.
• THIS MACHINE IS DESIGNED TO
BE RIDDEN BY THE OPERATOR
ONLY.
Do not carry passengers on this
machine.
• ALWAYS WEAR PROTECTIVE
APPAREL.
When operating this machine, al-
ways wear an approved helmet with
goggles or a face shield. Also wear
heavy boots, gloves, and protective
clothing. Always wear proper fitting
clothing that will not be caught in
any of the moving parts or controls
of the machine.• ALWAYS MAINTAIN YOUR MA-
CHINE IN PROPER WORKING
ORDER.
For safety and reliability, the ma-
chine must be properly maintained.
Always perform the pre-operation
checks indicated in this manual.
Correcting a mechanical problem
before you ride may prevent an ac-
cident.
• GASOLINE IS HIGHLY FLAMMA-
BLE.
Always turn off the engine while re-
fueling. Take care to not spill any
gasoline on the engine or exhaust
system. Never refuel in the vicinity
of an open flame, or while smoking.
• GASOLINE CAN CAUSE INJURY.
If you should swallow some gaso-
line, inhale excess gasoline vapors,
or allow any gasoline to get into
your eyes, contact a doctor immedi-
ately. If any gasoline spills onto
your skin or clothing, immediately
wash skin areas with soap and wa-
ter, and change your clothes.
• ONLY OPERATE THE MACHINE
IN AN AREA WITH ADEQUATE
VENTILATION.
Never start the engine or let it run
for any length of time in an enclosed
area. Exhaust fumes are poison-
ous. These fumes contain carbon
monoxide, which by itself is odor-
less and colorless. Carbon monox-
ide is a dangerous gas which can
cause unconsciousness or can be
lethal.
• PARK THE MACHINE CAREFUL-
LY; TURN OFF THE ENGINE.
Always turn off the engine if you are
going to leave the machine. Do not
park the machine on a slope or soft
ground as it may fall over.
• THE ENGINE, EXHAUST PIPE,
MUFFLER, AND OIL TANK WILL
BE VERY HOT AFTER THE EN-
GINE HAS BEEN RUN.
Be careful not to touch them or to
allow any clothing item to contact
them during inspection or repair.
• PROPERLY SECURE THE MA-
CHINE BEFORE TRANSPORTING
IT.
For safety, drain the gasoline from
the fuel tank before transporting the
vehicle.
4-33
BALANCER
BALANCER
REMOVING THE BALANCER
Order Part name Q'ty Remarks
Primary driven gear Refer to "CLUTCH" section.
Right crankcase cover Refer to "OIL FILTER ELEMENT AND WA-
TER PUMP" section.
Stator Refer to "AC MAGNETO" section.
1 Nut (balancer) 1 Refer to removal section.
2 Nut (primary drive gear) 1 Refer to removal section.
3 Nut (balancer shaft driven gear) 1 Refer to removal section.
4 Lock washer 1
5 Balancer 1
6 Straight key 1
7 Conical washer 1
8 Primary drive gear 1
9 Balancer shaft drive gear 1
10 Lock washer 1
11 Balancer shaft driven gear 1
4-34
BALANCER
REMOVING THE BALANCER
1. Straighten the lock washer tab.
2. Loosen:
• Nut (balancer) "1"
• Nut (primary drive gear) "2"
• Nut (balancer shaft driven gear)
"3"
Place an aluminum plate "a" between
the teeth of the balancer shaft drive
gear "4" and driven gear "5".
CHECKING THE PRIMARY DRIVE
GEAR, BALANCER SHAFT DRIVE
GEAR AND BALANCER SHAFT
DRIVEN GEAR
1. Inspect:
• Primary drive gear "1"
• Balancer shaft drive gear "2"
• Balancer shaft driven gear "3"
Wear/damage→Replace.CHECKING THE BALANCER
1. Inspect:
• Balancer
Cracks/damage → Replace.
INSTALLING THE BALANCER
1. Install:
• Balancer shaft driven gear "1"
Install the balancer shaft driven gear
and balancer shaft with their lower
splines "a" aligning with each other.
2. Install:
• Balancer shaft driven gear "1"
• Align the punched mark "a" on the
balancer shaft drive gear with the
punched mark "b" on the balancer
shaft driven gear.
• Install the balancer shaft driven
gear and crankshaft with the lower
splines "c" aligning with each other.
3. Install:
• Lock washer "1"
• Nut (balancer shaft driven gear)
"2"• Primary drive gear "3"
• Conical washer "4"
• Nut (primary drive gear) "5"
• Straight key "6"
• Balancer "7"
• Lock washer "8"
• Nut (balancer) "9"
• Apply molybdenum disulfide grease
to the contact surface and threaded
portion of the nut (primary drive
gear).
• Apply molybdenum disulfide grease
to the contact surface of the conical
spring washer.
• Place an aluminum plate "a" be-
tween the teeth of the balancer
shaft drive gear "10" and balancer
shaft driven gear "11".
• Install the conical washer with its
convex surface "b" outward.
4. Bend the lock washer tab.
Nut (balancer shaft driv-
en gear):
50 Nm (5.0 m•kg, 36
ft•lb)
Nut (primary drive gear):
100 Nm (10.0 m•kg, 72
ft•lb)
Nut (balancer):
45 Nm (4.5 m•kg, 33
ft•lb)
4-43
AC MAGNETO
AC MAGNETO
REMOVING THE AC MAGNETO
Order Part name Q'ty Remarks
Seat Refer to "SEAT AND SIDE COVERS" sec-
tion.
Fuel tank Refer to "FUEL TANK" section in the
CHAPER 6.
Disconnect the AC magneto lead
1 Left crankcase cover 1
2 Gasket 1
3 Dowel pin 2
4 Nut (rotor) 1 Refer to removal section.
5 Rotor 1 Refer to removal section.
6 Stator 1
7 Woodruff key 1
4-44
AC MAGNETO
REMOVING THE ROTOR
1. Remove:
• Nut (rotor) "1"
• Washer
2. Remove:
• Rotor "1"
Use the rotor puller 2.
CHECKING THE AC MAGNETO
1. Inspect:
• Rotor inner surface "a"
• Stator outer surface "b"
Damage → Inspect the crank-
shaft runout and crankshaft bear-
ing.
CHECKING THE WOODRUFF KEY
1. Inspect:
• Woodruff key "1"
Damage → Replace.INSTALLING THE AC MAGNETO
1. Install:
• Stator "1"
• Screw (stator) "2"
• Crankshaft position sensor "3"
• Holder "4"
• Bolt (crankshaft position sensor)
"5"
• Apply the sealant on the grommet
of the AC magneto lead.
• Tighten the screws using the T30
bit.
• Pass the crankshaft position sensor
lead "a" this side of the stator lead
"b".
• Install the holder so that the projec-
tion "c" on the holder contacts the
stopper.
2. Install:
• Woodruff key "1"
• Rotor "2"
• Degrease the contact surfaces of
the tapered portions of the crank-
shaft and rotor.
• When installing the woodruff key,
make sure that its flat surface "a" is
in parallel with the crankshaft center
line "b".
• When installing the rotor, align the
keyway "c" of the rotor with the
woodruff key.
3. Install:
• Washer
• Nut (rotor) "1"
4. Connect:
• AC magneto lead
Refer to "CABLE ROUTING DIA-
GRAM" section in the CHAPTER
2.
5. Install:
• Dowel pin
• Gasket (left crankcase cover)
• Left crankcase cover "1"
• Hose guide (cylinder head breath-
er hose) "2"
• Bolt (left crankcase cover)
Tighten the bolts in stage, using a
crisscross pattern.
Rotor puller:
YM-04151/90890-04151
Screw (stator):
8 Nm (0.8 m•kg,
5.8ft•lb)
Bolt (crankshaft position
sensor):
10 Nm (1.0 m•kg, 7.2
ft•lb)
YAMAHA Bond No. 1215
(ThreeBond
® No. 1215):
90890-85505
Nut (rotor):
65 Nm (6.5 m•kg, 47
ft•lb)
Bolt (left crankcase cov-
er):
10 Nm (1.0 m•kg, 7.2
ft•lb)