engine YAMAHA YZ85 2008 User Guide

OPERATION AND IMPORTANT RIDING POINTS
5-1
5
EAU41400
WARNING
EWA14610


This model is designed for off-
road use only. Become thor-
oughly familiar with all operat-
ing controls and their functions
before riding. Consult a Yamaha
dealer regarding any control or
function that you do not thor-
oughly understand.


Never start the engine or oper-
ate it in a closed area for any
length of time. Exhaust fumes
are poisonous, and inhaling
them can cause loss of con-
sciousness and death within a
short time. Always make sure
that there is adequate ventila-
tion.


Before starting out, make sure
that the sidestand is removed. If
the sidestand is not removed, it
will contact the ground, which
could distract the operator or af-
fect the balance of the motor-
cycle, resulting in a possibleloss of control.
EAU41301
Starting and warming up a
cold engine 1. Turn the fuel cock lever to “ON”.
2. Shift the transmission into the neu-
tral position.
3. Turn the starter (choke) on and
completely close the throttle. (See
page 3-6.)
4. Start the engine by pushing the
kickstarter lever down.CAUTION:
ECA11130
For maximum engine life, always
warm the engine up before starting
off. Never accelerate hard when theengine is cold!
5. When the engine is warm, turn the
starter (choke) off.NOTE:The engine is warm when it responds
normally to the throttle with the starter(choke) turned off.
EAU16660
Starting a warm engine Follow the same procedure as for start-
ing a cold engine with the exception
that the starter (choke) is not required
when the engine is warm. Instead, start
the engine with the throttle slightly
open.NOTE:If the engine does not start after several
kicks, try again with the throttle 1/4 to1/2 open.
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OPERATION AND IMPORTANT RIDING POINTS
5-2
5
EAU16671
Shifting Shifting gears lets you control the
amount of engine power available for
starting off, accelerating, climbing hills,
etc.
The gear positions are shown in the il-
lustration.NOTE:To shift the transmission into the neu-
tral position, press the shift pedal down
repeatedly until it reaches the end of itstravel, and then slightly raise it.
CAUTION:
ECA10260


Even with the transmission in
the neutral position, do not
coast for long periods of time
with the engine off, and do not
tow the motorcycle for long dis-
tances. The transmission is
properly lubricated only when
the engine is running. Inade-
quate lubrication may damage
the transmission.


Always use the clutch while
changing gears to avoid damag-
ing the engine, transmission,
and drive train, which are not
designed to withstand theshock of forced shifting.
EAU16690
To start out and accelerate
1. Pull the clutch lever to disengage
the clutch.
2. Shift the transmission into first
gear.
3. Open the throttle gradually and si-
multaneously release the clutch le-
ver slowly.4. Once the motorcycle has reached
a speed high enough to change
gears, close the throttle, and at the
same time, quickly pull the clutch
lever in.
5. Shift the transmission into second
gear. (Make sure not to shift the
transmission into the neutral posi-
tion.)
6. Open the throttle halfway and
gradually release the clutch lever.
7. Follow the same procedure when
shifting to the next gear.
EAU16710
To decelerate
1. Close the throttle and apply both
the front and the rear brakes to
slow the motorcycle.
2. Downshift through the gears and
shift the transmission into the neu-
tral position when the motorcycle
is almost completely stopped.
1. Shift pedal
2. Neutral positionU5PA86E0.book Page 2 Monday, April 9, 2007 3:16 PM

OPERATION AND IMPORTANT RIDING POINTS
5-3
5
EAU41502
Engine break-in 1. Before starting the engine, fill the
fuel tank with a break-in oil-fuel
mixture as follows.
2. Start and warm up the engine.
Check the operation of the controls
and the engine stop button. (See
page 3-1.)
3. Operate the motorcycle in the low-
er gears at moderate throttle open-
ings for five to eight minutes. Stop
the engine and check the spark
plug condition (see page 6-8); it
will show a rich condition during
break-in.
4. Allow the engine to cool. Restart
the engine and operate the motor-
cycle as in the step above for five
minutes. Then, very briefly shift to
the higher gears and check the
full-throttle response. Stop the en-
gine and check the spark plug.5. After again allowing the engine to
cool, restart and run the motor-
cycle for five more minutes. Full
throttle and the higher gears may
be used, but sustained full-throttle
operation should be avoided. Stop
the engine and check the spark
plug again.
6. Allow the engine to cool, remove
the cylinder head and cylinder, and
inspect the piston and cylinder.
Remove any high spots on the pis-
ton with #600-grit wet sandpaper.
Clean all components and careful-
ly reassemble the cylinder head
and cylinder.
WARNING
EWA10320
If you are not familiar with mainte-
nance work, have a Yamaha dealerdo it for you.
7. Drain the break-in oil-fuel mixture
from the fuel tank and refill with the
specified mix. (See page 3-3.)
8. Start the engine and check the op-
eration of the motorcycle through-
out its entire operating range. Stop
the engine and check the sparkplug condition. Restart the motor-
cycle and ride it for about 10 to 15
more minutes. The motorcycle will
now be ready to ride normally.
After the engine break-in period, thor-
oughly check the motorcycle for loose
parts, oil leakage and any other prob-
lems. Be sure to inspect and make ad-
justments thoroughly, especially cable
and drive chain slack and loose
spokes. In addition, check all fittings
and fasteners for looseness, and tight-
en if necessary.
CAUTION:
ECA15560


When any of the following parts
have been replaced, they must
be broken in.
Cylinder or crankshaft:
About one hour of break-in op-
eration is necessary.
Piston, rings or transmission
gears:
These parts require about 30
minutes of break-in operation at
half-throttle or less. Observe the
condition of the engine carefully
during operation.
Recommended 2-stroke engine oil:
See page 8-1.
Mixing ratio (gasoline to oil):
15:1
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OPERATION AND IMPORTANT RIDING POINTS
5-4
5


If any engine trouble should oc-
cur during the engine break-in
period, immediately have a
Yamaha dealer check the vehi-cle.
EAU17190
Parking When parking, stop the engine, and
then turn the fuel cock lever to “OFF”.
WARNING
EWA10310


Since the engine and exhaust
system can become very hot,
park in a place where pedestri-
ans or children are not likely to
touch them.


Do not park on a slope or on soft
ground, otherwise the vehiclemay overturn.
U5PA86E0.book Page 4 Monday, April 9, 2007 3:16 PM

PERIODIC MAINTENANCE AND MINOR REPAIR
6-8
6
EAU19612
Checking the spark plug The spark plug is an important engine
component, which is easy to check.
Since heat and deposits will cause any
spark plug to slowly erode, the spark
plug should be removed and checked
in accordance with the periodic mainte-
nance and lubrication chart. In addition,
the condition of the spark plug can re-
veal the condition of the engine.
To remove the spark plug
1. Remove the spark plug cap.
2. Remove the spark plug as shown,
with a spark plug wrench available
at a Yamaha dealer.To check the spark plug
1. Check that the porcelain insulator
around the center electrode of the
spark plug is a medium-to-light tan
(the ideal color when the vehicle is
ridden normally).
NOTE:
If the spark plug shows a distinctly dif-
ferent color, the engine could be oper-
ating improperly. Do not attempt to
diagnose such problems yourself. In-
stead, have a Yamaha dealer checkthe vehicle.2. Check the spark plug for electrode
erosion and excessive carbon or
other deposits, and replace it if
necessary.
To install the spark plug
1. Measure the spark plug gap with a
wire thickness gauge and, if nec-
essary, adjust the gap to specifica-
tion.
1. Spark plug cap
1. Spark plug wrench
Specified spark plug:
NGK/BR10EG1. Spark plug gapSpark plug gap:
0.5–0.6 mm (0.020–0.024 in)
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-9
6 2. Clean the surface of the spark plug
gasket and its mating surface, and
then wipe off any grime from the
spark plug threads.
3. Install the spark plug with the
spark plug wrench, and then tight-
en it to the specified torque.
NOTE:
If a torque wrench is not available when
installing a spark plug, a good estimate
of the correct torque is 1/4–1/2 turn
past finger tight. However, the spark
plug should be tightened to the speci-fied torque as soon as possible.
4. Install the spark plug cap.
EAU41441
Transmission oil The transmission oil must be checked
for oil leakage before each ride. If any
leakage is found, have a Yamaha deal-
er check and repair the motorcycle. In
addition, the transmission oil must be
changed at the intervals specified in the
periodic maintenance and lubrication
chart.
1. Start the engine, warm it up for
several minutes, and then turn it
off.
2. Place the motorcycle on a level
surface and hold it in an upright po-
sition.
3. Place an oil pan under the trans-
mission to collect the used oil.
4. Remove the oil filler cap and drain
bolt to drain the oil from the trans-
mission.5. Install the transmission oil drain
bolt, and then tighten it to the spec-
ified torque.
6. Add the specified amount of the
recommended transmission oil,
and then install and tighten the oil
filler cap.
Tightening torque:
Spark plug:
20 Nm (2.0 m·kgf, 14 ft·lbf)
1. Oil filler cap
2. Transmission oil drain bolt
Tightening torque:
Transmission oil drain bolt:
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Recommended transmission oil:
See page 8-1.
Oil change quantity:
0.50 L (0.53 US qt) (0.44 Imp.qt)
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-10
6
CAUTION:
ECA10452


In order to prevent clutch slip-
page (since the transmission oil
also lubricates the clutch), do
not mix any chemical additives.
Do not use oils with a diesel
specification of “CD” or oils of a
higher quality than specified. In
addition, do not use oils labeled
“ENERGY CONSERVING II” or
higher.


Make sure that no foreign mate-rial enters the transmission.
7. Start the engine, and then let it idle
for several minutes while checking
the transmission for oil leakage. If
oil is leaking, immediately turn the
engine off and check for the cause.
EAU20070
Coolant The coolant level should be checked
before each ride. In addition, the cool-
ant must be changed at the intervals
specified in the periodic maintenance
and lubrication chart.
EAUM1292
To check the coolant level
1. Place the vehicle on a level sur-
face and hold it in an upright posi-
tion.
WARNING
EWA10380
Never attempt to remove the radiatorcap when the engine is hot.
2. Remove the radiator cap and
check the coolant level in the radi-
ator.
NOTE:

The coolant level must be checked
on a cold engine since the level
varies with engine temperature.


Make sure that the vehicle is posi-
tioned straight up when checking
the coolant level. A slight tilt to theside can result in a false reading.
NOTE:The coolant should be at the bottom of
the radiator filler neck. The level will
change with variation of engine temper-ature.1. Radiator cap
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-11
6 3. If the coolant is below this level,
add coolant, and then install the
radiator cap.
NOTE:
If the engine overheats, see page 6-31for further instructions.
EAUM1312
To change the coolant
1. Place the vehicle on a level sur-
face and let the engine cool if nec-
essary.
2. Place a container under the engine
to collect the used coolant.
WARNING
EWA10380
Never attempt to remove the radiatorcap when the engine is hot.
3. Remove the coolant drain bolt and
then the radiator cap to drain the
cooling system.4. After the coolant is completely
drained, thoroughly flush the cool-
ing system with clean tap water.
5. Install the coolant drain bolt, and
then tighten it to the specified
torque.
NOTE:Check the washer for damage and re-place it if necessary.
6. Pour the recommended coolant
into the radiator until it is full.
1. Correct coolant level
1. Coolant drain bolt
1. Radiator cap
Tightening torque:
Coolant drain bolt:
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Antifreeze/water mixture ratio:
1:1
Recommended antifreeze:
High-quality ethylene glycol anti-
freeze containing corrosion inhibitors
for aluminum engines
Coolant quantity:
Radiator capacity (including all
routes):
0.54 L (0.57 US qt) (0.48 Imp.qt)
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-12
6
CAUTION:
ECA10471


If coolant is not available, use
distilled water or soft tap water
instead. Do not use hard water
or salt water since it is harmful
to the engine.


If water has been used instead
of coolant, replace it with cool-
ant as soon as possible, other-
wise the cooling system will not
be protected against frost and
corrosion.


If water has been added to the
coolant, have a Yamaha dealer
check the antifreeze content of
the coolant as soon as possible,
otherwise the effectiveness ofthe coolant will be reduced.
7. Install the radiator cap, start the
engine, let it idle for several min-
utes, and then turn it off.
8. Remove the radiator cap to check
the coolant level in the radiator. If
necessary, add sufficient coolant
until it reaches the bottom of the
radiator filler neck, and then install
the radiator cap.9. Start the engine, and then check
the vehicle for coolant leakage. If
coolant is leaking, have a Yamaha
dealer check the cooling system.
EAU41431
Cleaning the air filter element The air filter element should be cleaned
at the intervals specified in the periodic
maintenance and lubrication chart.
Clean the air filter element more fre-
quently if you are riding in unusually
wet or dusty areas.
1. Remove the seat. (See page 3-6.)
2. Remove the air filter case cover as
shown.1. Air filter case cover
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PERIODIC MAINTENANCE AND MINOR REPAIR
6-14
6
CAUTION:
ECA10480


Make sure that the air filter ele-
ment is properly seated in the
air filter case.


The engine should never be op-
erated without the air filter ele-
ment installed, otherwise the
piston(s) and/or cylinder(s) maybecome excessively worn.
9. Install the air filter case cover in the
original position as shown.
10. Install the seat.
EAU39930
Adjusting the carburetor The carburetor is an important part of
the engine and requires very sophisti-
cated adjustment. Therefore, most car-
buretor adjustments should be left to a
Yamaha dealer, who has the neces-
sary professional knowledge and expe-
rience. The adjustment described in the
following section, however, may be ser-
viced by the owner as part of routine
maintenance.CAUTION:
ECA10550
The carburetor has been set and ex-
tensively tested at the Yamaha fac-
tory. Changing these settings
without sufficient technical knowl-
edge may result in poor perfor-mance of or damage to the engine.
EAU44390
Adjusting the engine idling
speed The engine idling speed must be ad-
justed when necessary.
1. Start the engine and thoroughly
warm it up.
2. Turn the throttle stop screw until
the engine runs at the lowest pos-
sible speed.
3. To increase the engine idling
speed, turn the throttle stop screw
in direction (a). To decrease the
engine idling speed, turn the throt-
tle stop screw in direction (b).1. Throttle stop screw
U5PA86E0.book Page 14 Monday, April 9, 2007 3:16 PM