2003 YAMAHA YZ85 light

3 - 35
INSP
ADJ
LUBRICATION
LUBRICATION
To ensure smooth operation of all compo-
nents, lubricate your machine during setup,
after break-in, and after every race.
1All control cable
2Clutch lever pivot
3Shift pedal pivot
4Footrest pivot
5Throttle-to-handlebar contact
6Drive chain
7Tube guide cable winding portion
8Throttle cable end
9Clutch cable endÈUse Yamaha cable lube or equivalent on these
areas.
ÉUse SAE 10W-30 motor oil or suitable chain
lubricants.
ÊLubricate the following areas with high quality,
lightweight lithium-soap base grease.
CAUTION:
Wipe off any excess grease, and avoid get-
ting grease on the brake discs.
AAA
AAB
CC
5PA307705PA307805PA30790
5PA308005PA308105PA30820
5PA308005PA30840

3 - 36
INSP
ADJ
ELECTRICAL/SPARK PLUG INSPECTION
EC370000
ELECTRICAL
EC371001
SPARK PLUG INSPECTION
1. Remove:

Spark plug
2. Inspect:

Electrode 1
Wear/damage → Replace.

Insulator color 2
Normal condition is a medium to light tan
color.
Distinctly different color → Check the
engine condition.
NOTE:
When the engine runs for many hours at low
speeds, the spark plug insulator will become
sooty, even if the engine and carburetor are in
good operating condition.
3. Measure:

Plug gap a
Use a wire gauge or thickness gauge.
Out of specification → Regap.
4. Clean the plug with a spark plug cleaner if
necessary.
Spark plug gap:
0.5 ~ 0.6 mm (0.020 ~ 0.024 in)
5PA30850
5. Tighten:

Spark plug
NOTE:

Before installing a spark plug, clean the gas-
ket surface and plug surface.

Finger-tighten a the spark plug before torqu-
ing to specification b.
5PA30860
T R..20 Nm (2.0 m · kg, 1.4 ft · lb)

4 - 12
ENGCARBURETOR AND REED VALVE
Carburetor
1. Install:

Pilot air screw 1

Throttle stop screw 2
Note the following installation points:

Turn in the pilot air screw until it is lightly
seated.

Turn out the pilot air screw by the number
of turns recorded before removing.
Pilot air screw:
2 turns out (example)
5PA40260
2. Install:

Starter plunger 1
5PA40270
3. Install:

Pilot jet 1

Main nozzle 2

Main nozzle holder 3

Main jet 4
NOTE:
Install the main nozzle with its chamfered side
a facing the carburetor.
5PA40280
4. Install:

Needle valve 1

Float 2

Float pin 3
NOTE:

After installing the needle valve to the float,
install them to the carburetor.

Check the float for smooth movement.
5PA40290

4 - 54
ENG
REMOVAL POINTS
Crankcase
1. Remove:

Right crankcase 1
Use the crankcase separating tool 2.
NOTE:

Fully tighten the tool holding bolts, but make
sure the tool body is parallel with the case. If
necessary, one screw may be backed out
slightly to level tool body.

As pressure is applied, alternately tap on the
front engine mounting boss and transmission
shafts.
CAUTION:

Turn the segment 3 to the position
shown in the figure so that it does not
contact the crankcase.

Use soft hammer to tap on the case half.
Tap only on reinforced portions of case.
Do not tap on gasket mating surface.
Work slowly and carefully. Make sure the
case halves separate evenly. If one end
“hangs up”, take pressure off the push
screw, realign, and start over. If the cases
do not separate, check for a remaining
case screw or fitting. Do not force.
EC4N3301
Crankshaft
1. Remove:

Crankshaft 1
Use the crankcase separating tool 2.
NOTE:
Make appropriate bolts 3 as shown available
by yourself and attach the tool with them.
CAUTION:
Do not use a hammer to drive out the
crankshaft.
Crankcase separating tool:
YU-1135-A/90890-01135
Crankcase separating tool:
YU-1135-A/90890-01135
5PA41600
5PA41610
5PA41620
CRANKCASE AND CRANKSHAFT

4 - 58
ENG
4. Install:

Dowel pin 1

Right crankcase 2
To left crankcase 3.
NOTE:

Turn the shift cam 4 to the position shown in
the figure so that it does not contact the
crankcase when installing the crankcase.

Fit the right crankcase onto the left crank-
case. Tap lightly on the case with soft ham-
mer.

When installing the crankcase, the connect-
ing rod should be positioned at TDC (top
dead center).
5PA41760
5PA41770
5. Install:

Clamp 1

Screw (crankcase) 2
NOTE:
Tighten the crankcase tightening screws in
stage, using a crisscross pattern.
5PA41780
T R..8 Nm (0.8 m · kg, 5.8 ft · lb)
6. Install:

Crankcase oil seal holder 1

Bolt (crankcase oil seal holder) 2
7. Remove:

Sealant
Forced out on the cylinder mating surface.
8. Apply:

Engine oil
To the crank pin, bearing, oil delivery hole
and connecting rod end washer.
9. Check:

Crankshaft and transmission operation
Unsmooth operation → Repair.
5PAR0010
T R..20 Nm (2.0 m · kg, 14 ft · lb)
CRANKCASE AND CRANKSHAFT

4 - 60
ENG
EC4H3000
REMOVAL POINTS
Transmission
1. Remove:

Main axle 1

Drive axle 2
NOTE:

Remove assembly carefully. Note the posi-
tion of each part. Pay particular attention to
the location and direction of shift forks.

Remove the main axle and drive axle by tap-
ping lightly on the transmission drive axle
with a soft hammer.
5PA41800
EC4H4000
INSPECTION
EC4H4200
Gears
1. Inspect:

Matching dog a

Gear teeth b

Shift fork groove c
Wear/damage → Replace.
5PA41810
2. Check:

Gears movement
Unsmooth movement → Disassemble, and
then repair or replace.
5PA41820
EC4H4600
Bearing
1. Inspect:

Bearing 1
Rotate inner race with a finger.
Rough spot/seizure → Replace.
5PA41830
TRANSMISSION, SHIFT CAM AND SHIFT FORK

5 - 22
CHAS
Front brake hose
1. Install:

Copper washer 1

Brake hose 2

Union bolt 3
WARNING
Always use new copper washers.
CAUTION:
Install the brake hose so that its pipe por-
tion a directs as shown and lightly
touches the projection b on the brake
master cylinder.
5PA50660
T R..30 Nm (3.0 m · kg, 22 ft · lb)
5PA50670
2. Install:

Protector 1

Bolt (protector) 2
NOTE:
Fit the brake hose into the guides a of the pro-
tector.
5PA50680
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
3. Install:

Brake hose holder 1

Bolt (brake hose holder) 2
NOTE:

Align the brake hose holder with the projec-
tion a on the front fork and clamp the brake
hose.

Pass the brake hose behind the rib b on the
front fork.
5PA50690
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
FRONT BRAKE AND REAR BRAKE

5 - 23
CHAS
4. Install:

Copper washer 1

Brake hose 2

Union bolt 3
WARNING
Always use new copper washers.
CAUTION:
Install the brake hose so that its pipe por-
tion a lightly touches the projection b on
the brake caliper.
5PA50700
5PA50710
T R..26 Nm (2.6 m · kg, 19 ft · lb)
Rear brake hose
1. Install:

Copper washer 1

Brake hose 2

Union bolt 3
WARNING
Always use new copper washers.
CAUTION:
Install the brake hose so that its pipe por-
tion a directs as shown and lightly
touches the projection b on the brake
master cylinder.
5PA50720
5PA50730
T R..26 Nm (2.6 m · kg, 19 ft · lb)
FRONT BRAKE AND REAR BRAKE