engine YAMAHA YZ85 2006 Workshop Manual

4 - 51
ENG
EC4M3000
REMOVAL POINTS
EC4F3100
Drive sprocket
1. Remove:

Nut (drive sprocket) 1

Lock washer 2
NOTE:

Straighten the lock washer tab.

Loosen the nut while applying the rear brake.5PA41510
2. Remove:

Drive sprocket 1

Drive chain 2
NOTE:
Remove the drive sprocket together with the
drive chain.
5PA41520
EC4M3301
Engine removal
1. Remove:

Pivot shaft 1
NOTE:
If the pivot shaft is pulled all the way out, the
swingarm will come loose. If possible, insert a
shaft of similar diameter into the other side of
the swingarm to support it.5PA41530
2. Remove:

Engine 1
From right side.
NOTE:
Make sure that the couplers, hoses and cables
are disconnected.
5PA41540
ENGINE REMOVAL

4 - 52
ENG
EC4M5000
ASSEMBLY AND INSTALLATION
Engine installation
1. Install:

Engine 1
Install the engine from right side.

Pivot shaft 2

Engine mounting bolt (front) 3

Engine mounting bolt (lower) 4
NOTE:
Apply the molybdenum disulfide grease on the
pivot shaft.
5PA41550
T R..63 Nm (6.3 m · kg, 45 ft · lb)
T R..69 Nm (6.9 m · kg, 50 ft · lb)
T R..69 Nm (6.9 m · kg, 50 ft · lb)
Drive sprocket
1. Install:

Drive sprocket 1

Drive chain 2
NOTE:
Install the drive sprocket together with the
drive chain.
5PA41560
2. Install:

Lock washer 1

Nut (drive sprocket) 2
NOTE:
Tighten the nut while applying the rear brake.
3. Bend the lock washer tab to lock the nut.
5PA41570
T R..60 Nm (6.0 m · kg, 43 ft · lb)
4. Install:

Gasket (left crankcase cover)

Left crankcase cover 1

Screw (left crankcase cover) 2
NOTE:
Tighten the screws in stage, using a crisscross
pattern.
5PA41580
T R..5 Nm (0.5 m · kg, 3.6 ft · lb)
ENGINE REMOVAL

4 - 53
ENG
CRANKCASE AND CRANKSHAFT
5PAR0009
Extent of removal:
1 Crankcase separation
2 Crankshaft removal
3 Crankshaft bearing removal
Extent of removal Order Part name Q’ty Remarks
CRANKCASE AND CRANK-
SHAFT REMOVAL
Preparation for removal Engine Refer to “ENGINE REMOVAL” section.
Piston Refer to “CYLINDER HEAD, CYLINDER
AND PISTON” section.
Primary drive gear
Refer to “KICK SHAFT, SHIFT SHAFT
AND PRIMARY DRIVE GEAR” section. Kick idle gear
Stopper lever assembly
Rotor and stator Refer to “CDI MAGNETO” section.
1 Screw (crankcase) 11
2 Crankcase oil seal holder 1
3 Right crankcase 1
Use special tool.
Refer to “REMOVAL POINTS”.
4 Left crankcase 1
5 Crankshaft 1 Use special tool.
Refer to “REMOVAL POINTS”.
6 Oil seal 2
7 Bearing 2 Refer to “REMOVAL POINTS”.
2
1
3
CRANKCASE AND CRANKSHAFT

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 - 55
ENG
EC4N3401
Crankshaft bearing
1. Remove:

Bearing 1
NOTE:

Remove the bearing from the crankcase by
pressing its inner race as shown in È.

If the bearing is removed together with the
crankshaft, remove the bearing using a gen-
eral bearing puller 2 as shown in É.

Do not use the removed bearing.
5PA41630
EC4N4000
INSPECTION
Crankcase
1. Inspect:

Contacting surface a
Scratches → Replace.

Engine mounting boss b, crankcase
Cracks/damage → Replace.
5PA41650
2. Inspect:

Bearing 1
Rotate inner race with a finger.
Rough spot/seizure → Replace.
5PA41660
3. Inspect:

Oil seal 1
Damage → Replace.
5PA41670
È
É
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 - 59
ENG
EC4H0000
TRANSMISSION, SHIFT CAM AND SHIFT FORK
5PA41790
Extent of removal:
1 Shift cam and shift fork removal
2 Main axle and drive axle removal
Extent of removal Order Part name Q’ty Remarks
TRANSMISSION, SHIFT CAM
AND SHIFT FORK REMOVAL
Preparation for removal Engine Refer to “ENGINE REMOVAL” section.
Separate the crankcase. Refer to “CRANKCASE AND CRANK-
SHAFT” section.
1 Guide bar (long) 1
2 Guide bar (short) 1
3Shift cam 1
4 Shift fork 3 1
5 Shift fork 1 1
6 Shift fork 2 1
7 Main axle 1
Refer to “REMOVAL POINTS”.
8 Drive axle 1
9 Collar 1
1
2
TRANSMISSION, SHIFT CAM AND SHIFT FORK

5 - 1
CHAS
EC500000
CHASSIS
EC590000
FRONT WHEEL AND REAR WHEEL
EC598000
FRONT WHEEL
FRONT WHEEL AND REAR WHEEL
Extent of removal:
1 Front wheel removal
2 Wheel bearing removal
3 Brake disc removal
Extent of removal Order Part name Q’ty Remarks
Preparation for removalFRONT WHEEL REMOVAL
Hold the machine by placing the
suitable stand under the engine.
WARNING
Support the machine securely so there is nodanger of it falling over.
1 Nut (front wheel axle) 1
2 Front wheel axle 1
3 Front wheel 1
4 Collar 2
5 Oil seal 2
6 Bearing 2 Refer to “REMOVAL POINTS”.
7 Brake disc 1
2
31
3
5PA50010

5 - 2
CHAS
EC598100
REAR WHEEL
5PAR0012
Extent of removal:
1 Rear wheel removal
2 Wheel bearing removal
3 Brake disc removal
Extent of removal Order Part name Q’ty Remarks
Preparation for removalREAR WHEEL REMOVAL
Hold the machine by placing the
suitable stand under the engine.
WARNING
Support the machine securely so there is no
danger of it falling over.
1 Nut (rear wheel axle) 1
2 Rear wheel axle 1
3 Drive chain puller 2
4 Rear wheel 1 Refer to “REMOVAL POINTS”.
5 Collar 2
6 Rear wheel sprocket 1
7 Oil seal 2
8 Circlip 1
9 Bearing 2 Refer to “REMOVAL POINTS”.
10Brake disc
1
2
31
3
FRONT WHEEL AND REAR WHEEL

5 - 9
CHASFRONT BRAKE AND REAR BRAKE
EC5A0000
FRONT BRAKE AND REAR BRAKE
EC5A8000
FRONT BRAKE
5PA50250
Extent of removal:
1 Brake hose removal
2 Brake caliper removal
3 Brake master cylinder removal
Extent of removal Order Part name Q’ty Remarks
Preparation for removalFRONT BRAKE REMOVAL
Hold the machine by placing the
suitable stand under the engine.
WARNING
Support the machine securely so there is no
danger of it falling over.
Drain the brake fluid. Refer to “REMOVAL POINTS”.
1 Protector 1
2 Brake hose holder 1
3 Union bolt 2
4 Brake hose 1
5 Brake caliper support bolt 1
6 Brake caliper 1 Refer to “REMOVAL POINTS”.
7Brake lever 1
8 Brake master cylinder bracket 1
9 Brake master cylinder 1
2
3
132