fuel YAMAHA YZ85 2002 User Guide

GEN
INFO
1 - 16
TORQUE-CHECK POINTS
TORQUE-CHECK POINTS
Frame construction
Combined seat and fuel tank
Engine mounting
Steering Steering stem to
handlebar
Suspension Front Steering stem to front
fork
Rear For link type
Rear Installation of rear
shock absorber
Rear Installation of swin-
garm
Wheel Installation of wheel Front
Rear
Brake Front
Rear
Fuel systemFrame to rear frame
Fuel tank to frame
Frame to engine
Steering stem to upper bracket
Upper bracket to handlebar
Front fork to upper bracket
Front fork to lower bracket
Assembly of links
Link to frame
Link to rear shock absorber
Link to swingarm
Rear shock absorber to frame
Tightening of pivot shaft
Tightening of wheel axle
Tightening of wheel axle
Wheel to rear wheel sprocket
Brake caliper to front fork
Brake disc to wheel
Tightening of union bolt
Brake master cylinder to handlebar
Tightening of bleed screw
Brake caliper to bracket
Brake disc to wheel
Tightening of union bolt
Brake master cylinder to frame
Tightening of bleed screw
Fuel tank to fuel cock
NOTE:
Concerning the tightening torque, refer to
“MAINTENANCE SPECIFICATIONS” section
in the CHAPTER 2.

1 - 18
GEN
INFO
CLEANING AND STORAGE
EC1B2001
STORAGE
If your machine is to be stored for 60 days or
more, some preventive measures must be
taken to avoid deterioration. After cleaning the
machine thoroughly, prepare it for storage as
follows:
1. Drain the fuel tank, fuel lines, and the car-
buretor float bowl.
2. Remove the spark plug, pour a tablespoon
of SAE 10W-30 motor oil in the spark plug
hole, and reinstall the plug. With the engine
stop switch pushed in, kick the engine over
several times to coat the cylinder walls with
oil.
3. Remove the drive chain, clean it thoroughly
with solvent, and lubricate it. Reinstall the
chain or store it in a plastic bag tied to the
frame.
4. Lubricate all control cables.
5. Block the frame up to raise the wheels off
the ground.
6. Tie a plastic bag over the exhaust pipe out-
let to prevent moisture from entering.
7. If the machine is to be stored in a humid or
salt-air environment, coat all exposed
metal surfaces with a film of light oil. Do not
apply oil to rubber parts or the seat cover.
NOTE:
Make any necessary repairs before the
machine is stored.

SPEC
2 - 1
GENERAL SPECIFICATIONS
EC200000
SPECIFICATIONS
EC211000
GENERAL SPECIFICATIONS
Model name: YZ85 YZ85LW
YZ85P1 (USA)
YZ85LC (EUROPE)
YZ85(P)
(CDN, AUS, NZ, ZA)YZ85LW (EUROPE)
YZ85LWP (AUS, NZ)
Model code number: YZ85 YZ85LW
5PA1
(USA, CDN, EUROPE,
NZ, ZA)
5PA2
(AUS)5SH1
(EUROPE, NZ)
5SH2
(AUS)
Dimensions: YZ85 YZ85LW
Overall length 1,821 mm (71.7 in) 1,896 mm (74.4 in)
(USA, S, NZ, ZA)
1,818 mm (71.6 in)
(F, D, I, GB, E, CDN,
AUS)
Overall width 758 mm (28.9 in)¬
Overall height 1,161 mm (45.7 in) 1,204 mm (47.4 in)
Seat height 864 mm (34.0 in) 902 mm (35.0 in)
Wheelbase 1,258 mm (49.5 in) 1,278 mm (50.3 in)
(USA, S, NZ, ZA)
1,255 mm (49.4 in)
(F, D, I, GB, E, CDN,
AUS)
Minimum ground clearance 351 mm (13.8 in) 391 mm (15.4 in)
Basic weight: YZ85 YZ85LW
With oil and full fuel tank 71 kg (156.5 lb) 73.9 kg (162.9 lb)
Engine:
Engine type Liquid cooled 2-stroke, gasoline
Cylinder arrangement Single cylinder, forward inclined
Displacement 84.7 cm
3 (2.98 lmp oz, 2.86 US oz)
Bore ´ stroke 47.5 ´ 47.8 mm (1.870 ´ 1.882 in)
Compression ratio 8.2 : 1
Starting system Kickstarter
Lubrication system: Premix (30 : 1) (Yamalube 2-R)
Oil type or grade (2-cycle):
Transmission oil Yamalube 4 (10W-30) or SAE 10W-30 type SE
motor oil
Periodic oil change 0.50 L (0.44 lmp qt, 0.52 US qt)
Total amount 0.55 L (0.48 lmp qt, 0.58 US qt)
Coolant capacity (including all routes): 0.54 L (0.48 Imp qt, 0.57 US qt)
Air filter: Wet type element
2

2

SPEC
2 - 2
GENERAL SPECIFICATIONS
Fuel:
Type Premium unleaded gasoline only with a
research octane number of 95 or higher.
Tank capacity 5.0 L (1.10 Imp gal, 1.32 US gal)
Carburetor:
Type/manufacturer PWK28/KEIHIN
Spark plug:
Type/manufacturer BR10EG/NGK
Gap 0.5 ~ 0.6 mm (0.020 ~ 0.024 in)
Clutch type: Wet, multiple-disc
Transmission: YZ85 YZ85LW
Primary reduction system Gear¬
Primary reduction ratio 65/18 (3.611)¬
Secondary reduction system Chain drive¬
Secondary reduction ratio 47/14 (3.357) 52/14 (3.714)
(USA, S, NZ, ZA)
48/14 (3.429)
(F, D, I, GB, E, CDN,
AUS)
Transmission type Constant mesh,
6-speed¬
Operation Left foot operation¬
Gear ratio: 1st 27/11 (2.454)¬
2nd 32/17 (1.882)¬
3rd 26/17 (1.529)¬
4th 22/17 (1.294)¬
5th 26/23 (1.130)¬
6th 25/25 (1.000)¬
Chassis: YZ85 YZ85LW
Frame type Semi double cradle¬
Caster angle 26.3° 27°
Trail 88 mm (3.46 in) 106 mm (4.17 in)
Tire: YZ85 YZ85LW
Type With tube¬
Size (front) 70/100-17 40M 70/100-19 42M
Size (rear) 90/100-14 49M 90/100-16 52M
Tire pressure (front and rear) 100 kPa
(1.0 kg/cm
2, 15 psi)¬
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)

2

SPEC
2 - 13
MAINTENANCE SPECIFICATIONS
NOTE:
- marked portion shall be checked for torque tightening after break-in or before each race.Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Nipple (spoke) — 64 3 0.3 2.2
Rear wheel sprocket M8 ´ 1.25 4 42 4.2 30
Rear brake caliper protector M6 ´ 1.0 1 10 1.0 7.2
Engine mounting:
Engine and frame (front) M10 ´ 1.25 1 69 6.9 50
Engine and frame (lower) M10 ´ 1.25 1 69 6.9 50
Pivot shaft and nut M12 ´ 1.25 1 63 6.3 45
Relay arm and frame M10 ´ 1.25 1 54 5.4 39
Relay arm and connecting rod M12 ´ 1.25 1 53 5.3 38
Connecting rod and swingarm M12 ´ 1.25 1 53 5.3 38
Rear shock absorber and frame M10 ´ 1.25 1 36 3.6 25
Rear shock absorber and relay arm M10 ´ 1.25 1 36 3.6 25
Rear frame (upper) M8 ´ 1.25 1 26 2.6 19
Rear frame (lower) M8 ´ 1.25 2 16 1.6 11
Swingarm and brake hose holder M5 ´ — 4 4 0.4 2.9
Drive chain tensioner (upper) M8 ´ 1.25 1 23 2.3 17
Drive chain tensioner (lower) M6 ´ 1.0 1 10 1.0 7.2
Drive chain case M8 ´ 1.25 2 11 1.1 8
Seal guard and swingarm M6 ´ 1.0 2 10 1.0 7.2
Fuel tank M6 ´ 1.0 2 7 0.7 5.1
Fuel cock M6 ´ 1.0 2 4 0.4 2.9
Fuel tank bracket and fuel tank M6 ´ 1.0 4 7 0.7 5.1
Seat set bracket and fuel tank M6 ´ 1.0 1 7 0.7 5.1
Radiator cover M6 ´ 1.0 3 4 0.4 2.9
Front fender M6 ´ 1.0 4 7 0.7 5.1
Rear fender M6 ´ 1.0 4 7 0.7 5.1
Flap guard M6 ´ 1.0 2 7 0.7 5.1
Side cover M6 ´ 1.0 2 7 0.7 5.1
Seat M6 ´ 1.0 2 7 0.7 5.1
Number plate M6 ´ 1.0 1 7 0.7 5.1

2 - 16
SPEC
EC240000
CABLE ROUTING DIAGRAM
1Hose guide
2Brake hose
3Throttle cable
4Fuel tank breather hose
5Engine stop switch lead
6CDI magneto lead
7Clamp
8Carburetor breather hose
9Carburetor overflow hose
0Transmission oil breather hose
ARadiator breather hose
BClutch cable
CSpark plug leadDCable guide
EBrake hose holder
ÈPass the fuel tank breather hose between the
handlebar and tension bar, then insert its end
into the hole of the steering stem.
ÉFasten the ground lead together with the ignition
coil.
ÊClamp the brake hose with the brake hose
holder.
ËFit the brake hose into the guides of the protec-
tor.
CABLE ROUTING DIAGRAM

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