2002 YAMAHA YZ85 fuel

3 - 2
INSP
ADJ
MAINTENANCE INTERVALS
COOLING SYSTEM
Check coolant level and leakage
Check radiator cap operation
Replace coolant
Inspect hoses
ll
ll
l
Every two years
OUTSIDE NUTS AND BOLTS
Retighten
ll
AIR FILTER
Clean and lubricate
Replace
ll
lUse foam air-filter oil
FRAME
Clean and inspect
ll
FUEL TANK, COCK
Clean and inspect
ll
BRAKES
Adjust lever position and pedal height
Lubricate pivot point
Check brake disc surface
Check fluid level and leakage
Retighten brake disc bolts, caliper
bolts, master cylinder bolts and union
bolts
Replace pads
Replace brake fluid
l
l
l
l
ll
l
l
l
l
l
l
Every one year
FRONT FORKS
Inspect and adjust
Replace oil
Replace oil seal
l
ll
l
l
Suspension oil “01”
FRONT FORK OIL SEAL AND DUST
SEAL
Clean and lube
llLithium base grease
REAR SHOCK ABSORBER
Inspect and adjust
Lube
Retighten
l
ll
ll(After
rain ride)
l
Molybdenum disulfide
grease
CHAIN GUARD AND ROLLERS
Inspect
l
SWINGARM
Inspect and retighten
Lube
l
ll
l
Molybdenum disulfide
grease
RELAY ARM, CONNECTING ROD
Inspect and retighten
Lube
l
ll
l
Molybdenum disulfide
grease
STEERING HEAD
Inspect free play and retighten
Clean and lube
Replace bearing
ll
l
l
Lithium base grease ItemAfter
break-inEvery
raceEvery
third
raceEvery
fifth
raceAs re-
quiredRemarks


3

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 cap.
Check the cooling system for leakage.P.3-5 ~ 9
FuelCheck that a fresh mixture of oil and gasoline is filled in the fuel
tank. Check the fuel line for leakage.P.1-12
Transmission oilCheck that the oil level is correct. Check the crankcase for leak-
age.P.3-12 ~ 13
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
Brakes Check the play of front brake and effect of front and rear brake. P.3-16 ~ 21
Drive chainCheck drive chain slack and alignment. Check that the drive
chain is lubricated properly.P.3-22 ~ 24
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-31 ~ 32
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-32 ~ 33
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage. P.3-24 ~ 30
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.—
Exhaust pipe and silencerCheck that the exhaust pipe is tightly mounted and has no
cracks.P.4-2
Rear wheel sprocket Check that the rear wheel sprocket tightening bolt is not loose. P.3-22
Lubrication Check for smooth operation. Lubricate if necessary. P.3-34
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-16
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 ~ 19

3 - 14
INSP
ADJ
PILOT AIR SCREW ADJUSTMENT
1. Adjust:
lPilot air screw 1
Adjustment steps:
NOTE:
To optimize the fuel flow at a smaller throttle
opening, each machine’s pilot air screw has
been individually set at the factry. Before
adjusting the pilot air screw, turn it in fully and
count the number of turns. Record this num-
ber as the factry-set number of turns out.
lTurn in the pilot air screw until it is lightly
seated.
lTurn out the pilot air screw by the speci-
fied number of turns.
Pilot air screw:
2 turns out (example)
5PA30230
ENGINE IDLING SPEED ADJUSTMENT
1. Start the engine and thoroughly warm it up.
2. Adjust:
lEngine idling speed
Adjustment steps:
lTurn the throttle stop screw 1 until the
engine runs at the lowest possible speed.
To increase idle speed ® Turn the throt-
tle stop screw 1 in a.
To decrease idle speed ® Turn the throt-
tle stop screw 1 out b.
5PA30240
EXHAUST PIPE INSPECTION
1. Inspect:
lO-ring 1
Damage ® Replace.
NOTE:
Install the O-rings with their depressed a fac-
ing inward.
5PA30250
PILOT AIR SCREW ADJUSTMENT/ENGINE IDLING
SPEED ADJUSTMENT/EXHAUST PIPE INSPECTION

3 - 33
INSP
ADJ
STEERING HEAD INSPECTION AND ADJUSTMENT
lTighten the steering ring nut 3 using
steering nut wrench 4.
NOTE:
Set the torque wrench to the steering nut
wrench so that they form a right angle.
Steering nut wrench:
YU-33975/90890-01403
T R..
Steering ring nut (initial tighten-
ing):
38 Nm (3.8 m • kg, 27 ft • lb)
lLoosen the steering ring nut one turn.
lRetighten the steering ring nut using the
steering nut wrench.
WARNING
Avoid over-tightening.
T R..
Steering ring nut (final tighten-
ing):
4 Nm (0.4 m • kg, 2.9 ft • lb)
lCheck the steering stem by turning it lock
to lock. If there is any binding, remove the
steering stem assembly and inspect the
steering bearings.
lInstall the upper bracket 5, steering stem
nut 6, handlebar 7, handlebar upper
holder 8 and number plate 9.
NOTE:
lThe upper handlebar holder should be
installed with the punched mark a for-
ward.
lInsert the end of fuel breather hose 0 into
the hole of the steering stem.
CAUTION:
First tighten the bolts on the front side of
the handlebar holder, and then tighten
the bolts on the rear side.
T R..
Steering stem nut:
115 Nm (11.5 m • kg, 85 ft • lb)
Handlebar upper holder:
27 Nm (2.7 m • kg, 19 ft • lb)
Pinch bolt (upper bracket):
22 Nm (2.2 m • kg, 16 ft • lb)
Number plate:
7 Nm (0.7 m • kg, 5.1 ft • lb)
5PA30750
5PA30760

4 - 1
ENG
EC400000
ENGINE
SEAT, FUEL TANK AND SIDE COVERS
5PA40010
Extent of removal:
1 Seat removal
2 Fuel tank removal
3 Side covers removal
4 Number plate removal
Extent of removal Order Part name Q’ty Remarks
Preparation for removalSEAT, FUEL TANK AND SIDE
COVERS REMOVAL
Turn the fuel cock to “OFF”.
Disconnect the fuel hose.
1Seat 1
2 Air scoop 1
3 Bolt (fuel tank) 2
4 Fuel tank 1
5 Left side cover 1
6 Right side cover 1
7 Number plate 1
13
4
2
3
SEAT, FUEL TANK AND SIDE COVERS
4



4

4 - 2
ENGEXHAUST PIPE AND SILENCER
EC4S0000
EXHAUST PIPE AND SILENCER
5PA40020
Extent of removal:
1 Silencer removal
2 Exhaust pipe removal
Extent of removal Order Part name Q’ty Remarks
EXHAUST PIPE AND
SILENCER REMOVAL
Preparation for removal Right side cover Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
1 Bolt (silencer) 1
2 Silencer 1
3 Exhaust pipe spring 2
4 Bolt (exhaust pipe) 2
5Exhaust pipe
1
1
2

4 - 3
ENGRADIATOR
EC450001
RADIATOR
5PA40030
Extent of removal:
1 Radiator removal
Extent of removal Order Part name Q’ty Remarks
RADIATOR REMOVAL
Preparation for removal Drain the coolant. Refer to “COOLANT REPLACEMENT”
section in the CHAPTER 3.
Air scoop Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
1 Radiator guard 1
2 Radiator hose clamp 4 Only loosening.
3 Radiator hose 1 1
4 Radiator hose 2 1
5Radiator 1
6 Radiator breather hose 1
1

4 - 8
ENGCARBURETOR AND REED VALVE
HANDLING NOTE
CAUTION:
Do not disassemble the venturi block
1
because it will cause a drop in carburetor
performance.
5PA40110
EC463000
REMOVAL POINTS
EC463110
Throttle valve
1. Remove:
lThrottle valve 1
lRing 2
lSpring (throttle valve) 3
lMixing chamber top 4
lThrottle cable 5
NOTE:
While compressing the spring (throttle valve),
disconnect the throttle cable.
5PA40120
INSPECTION
Pilot air screw
1. Remove:
lPilot air screw 1
NOTE:
To optimize the fuel flow at a small throttle
opening, each machine’s pilot air screw has
been individually set at the factory. Before
removing the pilot air screw, turn it in fully and
count the number of turns. Record this number
as the factory-set number of turns out.
Carburetor
1. Inspect:
lCarburetor body
Contamination ® Clean.
NOTE:
lUse a petroleum based solvent for cleaning.
Blow out all passages with compressed air.
lNever use a wire.
5PA40130
5PA40130