2008 YAMAHA YZ85 engine

TABLE OF CONTENTS
SAFETY INFORMATION .................. 1-1
Safe riding ....................................... 1-1
Location of important labels ........... 1-4
DESCRIPTION .................................. 2-1
Left view .......................................... 2-1
Right view ........................................ 2-2
Controls and instruments ................2-3
INSTRUMENT AND CONTROL
FUNCTIONS....................................... 3-1
Handlebar switch ............................ 3-1
Clutch lever .................................... 3-1
Shift pedal ......................................3-1
Brake lever ..................................... 3-2
Brake pedal .................................... 3-2
Fuel tank cap .................................. 3-3
Fuel ................................................ 3-3
Fuel tank breather hose ................. 3-5
Fuel cock ........................................ 3-5
Starter (choke) knob ....................... 3-6
Kickstarter ......................................3-6
Seat ................................................ 3-6
Adjusting the front fork ................... 3-7
Front fork bleeding ......................... 3-8
Adjusting the shock absorber
assembly ..................................... 3-9
Removable sidestand ................... 3-12
PRE-OPERATION CHECKS.............. 4-1
Pre-operation check list .................. 4-2OPERATION AND IMPORTANT
RIDING POINTS................................ 5-1
Starting and warming up a cold
engine ......................................... 5-1
Starting a warm engine .................. 5-1
Shifting ........................................... 5-2
Engine break-in .............................. 5-3
Parking ........................................... 5-4
PERIODIC MAINTENANCE AND
MINOR REPAIR................................. 6-1
Periodic maintenance and
lubrication chart .......................... 6-2
Checking the spark plug ................ 6-8
Transmission oil ............................. 6-9
Coolant ........................................ 6-10
Cleaning the air filter element ...... 6-12
Adjusting the carburetor ............... 6-14
Adjusting the engine idling
speed ........................................ 6-14
Adjusting the throttle cable free
play ........................................... 6-15
Tires ............................................. 6-15
Spoke wheels .............................. 6-17
Accessories and replacement
parts ......................................... 6-17
Adjusting the clutch lever free
play ........................................... 6-18
Checking the front brake lever
free play .................................... 6-18Checking the front and rear
brake pads ................................ 6-19
Checking the brake fluid level ...... 6-20
Changing the brake fluid .............. 6-21
Drive chain slack .......................... 6-21
Cleaning and lubricating the
drive chain ................................ 6-22
Checking and lubricating the
cables ....................................... 6-23
Checking and lubricating the
throttle grip and cable ............... 6-23
Checking and lubricating the
brake and shift pedals ............... 6-24
Checking and lubricating the
brake and clutch levers ............. 6-24
Lubricating the swingarm pivots ... 6-25
Lubricating the rear suspension ... 6-25
Checking the front fork ................. 6-25
Checking the steering .................. 6-26
Checking the wheel bearings ....... 6-27
Supporting the motorcycle ........... 6-27
Front wheel .................................. 6-28
Rear wheel ................................... 6-28
Troubleshooting ........................... 6-30
Troubleshooting charts ................. 6-31
MOTORCYCLE CARE AND
STORAGE.......................................... 7-1
Matte color caution ......................... 7-1
Care ............................................... 7-1
Storage ........................................... 7-3
U5PA86E0.book Page 1 Monday, April 9, 2007 3:16 PM

1-1
1
SAFETY INFORMATION
EAU41460
Safe riding

Always make pre-operation
checks. Careful checks may help
prevent an accident.


This motorcycle is designed for off-
road use only, therefore, it is illegal
to operate it on public streets,
roads, or highways, even a dirt or
gravel one. Off-road use on public
lands may be illegal. Please check
local regulations before riding.


This motorcycle is designed to car-
ry the operator only. No passen-
gers.


Many accidents involve inexperi-
enced operators.
Make sure that the operator is
qualified and that you only lend
your motorcycle to other quali-
fied operators.
Know your skills and limits.
Staying within your limits may
help you to avoid an accident.


Many accidents have been caused
by error of the motorcycle opera-
tor. A typical error made by the op-
erator is veering wide on a turn
due to EXCESSIVE SPEED or un-dercornering (insufficient lean an-
gle for the speed). Never travel
faster than warranted by condi-
tions.


Ride cautiously in unfamiliar ar-
eas. You may encounter hidden
obstacles that could cause an ac-
cident.


The posture of the operator is im-
portant for proper control. The op-
erator should keep both hands on
the handlebar and both feet on the
operator footrests during operation
to maintain control of the motor-
cycle.


Never ride under the influence of
alcohol or other drugs.


Be sure the transmission is in neu-
tral before starting the engine.
Protective apparel
The majority of fatalities from motor-
cycle accidents are the result of head
injuries. The use of a safety helmet is
the single most critical factor in the pre-
vention or reduction of head injuries.


Always wear an approved helmet.


Wear a face shield or goggles.
Wind in your unprotected eyes
could contribute to an impairment
of vision that could delay seeing a
hazard.


The use of a jacket, heavy boots,
trousers, gloves, etc., is effective in
preventing or reducing abrasions
or lacerations.


Never wear loose-fitting clothes,
otherwise they could catch on the
control levers, footrests, or wheels
and cause injury or an accident.


Never touch the engine or exhaust
system during or after operation.
They become very hot and can
cause burns. Always wear protec-
tive clothing that covers your legs,
ankles, and feet.
Modifications
Modifications made to this motorcycle
not approved by Yamaha, or the re-
moval of original equipment, may ren-
der the motorcycle unsafe for use and
may cause severe personal injury.
Modifications may also make your
motorcycle illegal to use.
U5PA86E0.book Page 1 Monday, April 9, 2007 3:16 PM

SAFETY INFORMATION
1-2
1Loading and accessories
Adding accessories to your motorcycle
can adversely affect stability and han-
dling if the weight distribution of the
motorcycle is changed. To avoid the
possibility of an accident, use extreme
caution when adding accessories to
your motorcycle. Use extra care when
riding a motorcycle that has added ac-
cessories. Here are some general
guidelines to follow if adding accesso-
ries to your motorcycle:
Loading


Accessory weight should be kept
as low and close to the motorcycle
as possible. Make sure to distrib-
ute the weight as evenly as possi-
ble on both sides of the motorcycle
to minimize imbalance or instabili-
ty.


Shifting weights can create a sud-
den imbalance. Make sure that ac-
cessories are securely attached to
the motorcycle before riding.
Check accessory mounts fre-
quently.


Never attach any large or heavy
items to the handlebar, front fork,
or front fender.Accessories
Genuine Yamaha accessories have
been specifically designed for use on
this motorcycle. Since Yamaha cannot
test all other accessories that may be
available, you must personally be re-
sponsible for the proper selection, in-
stallation and use of non-Yamaha
accessories. Use extreme caution
when selecting and installing any ac-
cessories.
Keep these guidelines in mind for
mounting accessories in addition to
those provided under “Loading”.

Never install accessories or that
would impair the performance of
your motorcycle. Carefully inspect
the accessory before using it to
make sure that it does not in any
way reduce ground clearance or
cornering clearance, limit suspen-
sion travel, steering travel or con-
trol operation.
Accessories fitted to the handle-
bar or the front fork area can
create instability due to improper
weight distribution or aerody-
namic changes. If accessories
are added to the handlebar orfront fork area, they must be as
lightweight as possible and
should be kept to a minimum.
Bulky or large accessories may
seriously affect the stability of
the motorcycle due to aerody-
namic effects. Wind may at-
tempt to lift the motorcycle, or
the motorcycle may become un-
stable in cross winds.
Certain accessories can dis-
place the operator from his or
her normal riding position. This
improper position limits the free-
dom of movement of the opera-
tor and may limit control ability,
therefore, such accessories are
not recommended.


Use caution when adding electri-
cal accessories. If electrical acces-
sories exceed the capacity of the
motorcycle’s electrical system an
electric failure could result, which
could cause a dangerous loss of
engine power.
U5PA86E0.book Page 2 Monday, April 9, 2007 3:16 PM

SAFETY INFORMATION
1-3
1 Gasoline and exhaust gas


GASOLINE IS HIGHLY FLAMMA-
BLE:
Be sure to always use a fresh
mixture of oil and gasoline.
Always turn the engine off when
refueling.
Take care not to spill any gaso-
line on the engine or exhaust
pipe/muffler when refueling.
Never refuel while smoking or in
the vicinity of an open flame.


Never start the engine or let it run
for any length of time in a closed
area. The exhaust fumes are poi-
sonous and may cause loss of
consciousness and death within a
short time. Always operate your
motorcycle in an area that has ad-
equate ventilation.


Always turn the engine off before
leaving the motorcycle unattend-
ed. When parking the motorcycle,
note the following:
The engine and exhaust
pipe/muffler may be hot, there-
fore, park the motorcycle in aplace where pedestrians or chil-
dren are not likely to touch these
hot areas.
Do not park the motorcycle on a
slope or soft ground, otherwise it
may fall over.
Do not park the motorcycle near
a flammable source (e.g., a ker-
osene heater, or near an open
flame), otherwise it could catch
fire.


When transporting the motorcycle
in another vehicle, make sure that
it is kept upright and that the fuel
cock is turned to “OFF”. If the
motorcycle should lean over, gas-
oline may leak out of the carbure-
tor or fuel tank.


If you should swallow any gaso-
line, inhale a lot of gasoline vapor,
or allow gasoline to get into your
eyes, see your doctor immediately.
If any gasoline spills on your skin
or clothing, immediately wash the
affected area with soap and water
and change your clothes.
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INSTRUMENT AND CONTROL FUNCTIONS
3-1
3
EAU40660
Handlebar switch
EAU12670
“ENGINE STOP” button
Hold this button pushed until the engine
stops in case of an emergency, such as
when the vehicle overturns or when the
throttle cable is stuck.
EAU12850
Clutch lever The clutch lever is located at the left
handlebar grip. To disengage the
clutch, pull the lever toward the handle-
bar grip. To engage the clutch, release
the lever. The lever should be pulled
rapidly and released slowly for smooth
clutch operation.
EAU12870
Shift pedal The shift pedal is located on the left
side of the engine and is used in com-
bination with the clutch lever when
shifting the gears of the 6-speed con-
stant-mesh transmission equipped on
this motorcycle.
1. Engine stop button “ENGINE STOP”
1. Clutch lever
1. Shift pedal
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INSTRUMENT AND CONTROL FUNCTIONS
3-3
3
EAU13181
Fuel tank cap To remove the fuel tank cap, turn it
counterclockwise, and then pull it off.
To install the fuel tank cap, insert it into
the tank opening, and then turn it clock-
wise.
WARNING
EWA11090
Make sure that the fuel tank cap isproperly closed before riding.
EAU41831
Fuel This motorcycle has been designed to
use a premixed fuel of gasoline and 2-
stroke engine oil. Always mix the gaso-
line and oil in a clean container before
filling the fuel tank.CAUTION:
ECA15601
Always use fresh gasoline, and fill
the fuel tank with a fresh mix just be-
fore riding. Do not use premixed fuelthat is more than a few hours old.
Mixing gasoline and 2-stroke engine
oil
Pour 2-stroke engine oil into a clean
container, and then add gasoline. To
mix the fuel thoroughly, shake the con-
tainer from side to side.
CAUTION:
ECA15590
Use only unleaded gasoline. The use
of leaded gasoline will cause severe
damage to internal engine parts,
such as the piston rings as well as tothe exhaust system.
1. Fuel tank cap
1. 2-stroke engine oil
2. Gasoline
3. ContainerRecommended fuel:
Premium unleaded gasoline only
Recommended 2-stroke engine oil:
See page 8-1.
Fuel tank capacity:
5.0 L (1.32 US gal) (1.10 Imp.gal)
Mixing ratios (gasoline to oil):
Break-in period: 15:1
After break-in: 30:1
U5PA86E0.book Page 3 Monday, April 9, 2007 3:16 PM

INSTRUMENT AND CONTROL FUNCTIONS
3-4
3 Your Yamaha engine has been de-
signed to use premium unleaded gaso-
line with a pump octane number
[(R+M)/2] of 91 or higher, or a research
octane number of 95 or higher. If
knocking (or pinging) occurs, use a
gasoline of a different brand.
If the recommended 2-stroke engine oil
is not available, use an equivalent oil.
CAUTION:
ECA15551
Never mix two brands of 2-stroke en-
gine oil in the same batch. Always
use the same type of oil to ensure
maximum engine performance.
Should it be necessary to use a dif-
ferent oil brand, be sure to drain the
fuel tank and the carburetor float
chamber of the old premixed fuelprior to filling with the new type.Filling the fuel tank
Make sure that there is sufficient fuel in
the tank. Fill the fuel tank to the bottom
of the filler tube as shown.
WARNING
EWA10880


Do not overfill the fuel tank, oth-
erwise it may overflow when the
fuel warms up and expands.


Avoid spilling fuel on the hot en-gine.
CAUTION:
ECA10070
Immediately wipe off spilled fuel
with a clean, dry, soft cloth, since
fuel may deteriorate painted surfac-es or plastic parts.
1. Fuel level
2. Fuel tank filler tube
U5PA86E0.book Page 4 Monday, April 9, 2007 3:16 PM

INSTRUMENT AND CONTROL FUNCTIONS
3-5
3
EAU41360
Fuel tank breather hose Before operating the motorcycle:

Check the fuel tank breather hose
connection.


Check the fuel tank breather hose
for cracks or damage, and replace
it if damaged.


Make sure that the end of the fuel
tank breather hose is not blocked,
and clean it if necessary.
NOTE:If the fuel tank breather hose falls out,
reinstall it on the fuel tank cap with the
arrow mark on the one-way valve point-ed downward as shown.
EAU41280
Fuel cock The fuel cock supplies fuel from the
tank to the carburetor while filtering it al-
so.
The fuel cock has two positions:
OFF
With the lever in this position, fuel will
not flow. Always return the lever to this
position when the engine is not running.ON
With the lever in this position, fuel flows
to the carburetor. Normal riding is done
with the lever in this position.
1. Fuel tank breather hose
2. One-way valve
1. Arrow mark positioned over “OFF”
1. Arrow mark positioned over “ON”
U5PA86E0.book Page 5 Monday, April 9, 2007 3:16 PM